Defects inspecting apparatus and defects inspecting method

ABSTRACT

An inspecting apparatus and method including first and second illuminating units for illuminating a surface of a specimen to be inspected with different incident angles and first and second detecting optical units arranged at different elevation angle directions to the surface of the specimen for detecting images of the specimen illuminated by the first and second illuminating units.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.10/536,715, filed Oct. 21, 2005, now U.S. Pat. No. 7,417,721, thecontents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a defects inspecting apparatus fordetecting defects, such as, foreign matters or particles (hereinafter,“foreign matters”, collectively), existing upon a thin-film substrate, asemiconductor substrate and/or a photo mask, etc., in particular, whenmanufacturing a semiconductor chip and/or a liquid crystal product, orscratches or the like, which are caused on a circuit pattern, therebyinspecting a situation of generating such foreign matters or the like,within a manufacturing process of devices, for analyzing the defects,such as, the foreign matters, etc., which are detected, as well as, amethod thereof.

BACKGROUND OF THE INVENTION

Within the manufacturing process of semiconductors, presence of theforeign matters on a semiconductor substrate (i.e., a wafer) comes to bea cause of generation of defects, such as, insulation failure (or, illinsulation) or short-circuiting between wiring patterns, etc. Further,accompanying with miniaturization of the semiconductor elements, suchthe foreign matters, but being fine or microscopic much more, also comesto be the reason of ill insulation of a capacitor and/or breakage ofgate oxidization films, etc. Thus, such the foreign matters, includingthose generated from movable portions of a conveyer, those generatedfrom a human body, those produced by processing gas through reactionthereof within a processing apparatus, and those mixed within chemicalsand materials, for example; they are mixed up with one another, undervarious conditions and due to various kinds of reasons thereof.

In the similar manner, within the manufacturing process of a liquidcrystal display device, the device results into the useless ifgenerating any kind of defects therein, such as, mixture of foreignmatters in the patterns thereon, for example. Also, being similar in thecondition mentioned above, within the manufacturing process of a printedcircuit board, mixture of the foreign matters also results intoshort-circuiting and/or ill connection of patterns thereon.

As one of such technologies relating to the conventional arts, fordetecting the foreign matters on the semiconductor substrate, forexample, in Japanese Patent Laying-Open No. Sho 62-89336(1987)<Conventional Art 1>, there is disclosed a technology of detectinglights scattered from foreign matters while irradiating a laser beamthereupon, being generated in a case when the foreign matters adhereupon the semiconductor substrate, and then making comparison thereof,with using the results of inspection obtained previously, upon the sameking of semiconductor substrate, so as to neglect a false report due tothe patterns thereon; thereby, enabling an inspection of foreign mattersand defects with high sensitivity and high reliability. Also, as isdisclosed in Japanese Patent Laying-Open No. Sho 63-135848 (1988)<Conventional Art 2>, for example, there is also known a technology ofdetecting lights scattered from foreign matters while irradiating alaser beam thereupon, being generated in a case when the foreign mattersadhere upon the surface of semiconductor substrate, and then analysis ismade upon the foreign matter detected, through the analyzing technology,such as, the laser photoluminescence or the secondary X-ray analysis(XMR), etc.

Also, as a technology for inspecting the above-mentioned foreignmatters, there is disclosed a method of removing the lights emitted fromrepetitive patterns upon a wafer when irradiating coherent lights uponthe wafer through a space filter(s), thereby detecting the foreignmatters and/or defects having no such repetitiveness, with emphasisthereof. Further, a foreign matter inspecting apparatus is also alreadyknown, for example, in Japanese Patent Laying-Open No. Hei 1-117024(1989)<Conventional Art 3>, in which apparatus a light is irradiatedupon circuit patterns formed on a wafer from a direction inclined by 45degree with respect to a group of main lines of the said circuitpatterns, thereby preventing the 0^(th)-order diffracted light fromentering into an opening of an objection lens. Moreover, as theconventional technologies relating to a defects inspecting apparatus anda method thereof, for inspecting foreign matters, etc., there are alsoalready known the followings: Japanese Patent Laying-open No. Hei1-250847 (1989)<Conventional Art 4>; Japanese Patent Laying-Open No. Hei6-258239 (1994)<Conventional Art 5>; Japanese Patent Laying-Open No. Hei6-324003 (1994)<Conventional Art 6>; Japanese Patent Laying-Open No. Hei8-210989 (1996)<Conventional Art 7>; Japanese Patent Laying-Open No. Hei8-271437 (1996)<Conventional Art 8>; and Japanese Patent Laying-Open No.2000-105203 (2000)<Conventional Art 9>. In particular, the conventionaltechnology 9 describes that a size of detecting pixel can be changedthrough exchanging a detection optic system. Also a technology formeasuring a size of foreign matter is disclosed in Japanese PatentLaying-Open No. 2001-60607 (2001)<Conventional Art 10> and JapanesePatent Laying-Open No. 2001-264264 (2001)<Conventional Art 11>, forexample.

DISCLOSURE OF THE INVENTION

However, with the Conventional Arts 1 through 9, it is impossible todetect the fine or microscopic foreign matters, or defects upon thesubstrate, easily, on which repetitive patterns and non-repetitivepatterns are formed mixing with each other, at high sensitivity and athigh-speed. Thus, with those Conventional Arts 1 through 9 mentionedabove, in particular, in a portion other than the repetitive portion,such as, a cell portion of a memory, for example, there is a problemthat the detection sensitivity is low (i.e., the minimum size of adetectable foreign matter is large). Also, with the Conventional Arts 1through 9 mentioned above, there is other problem that the detectionsensitivity is low on the fine foreign matters or defects, such as, alevel of 0.1 μm, in particular, within a region where the patterndensity is high. Further, with the Conventional Arts 1 through 9mentioned above, there is other problem that the detection sensitivityis also low, in particular, on the foreign matters or defects, whichbuild up short-circuiting between the wiring patterns, or on a film-likedefects. Or, with the Conventional Arts 10 and 11 mentioned above, thereis a problem that accuracy is low, in particular, when measuring theforeign matters or the defects. Also, with the Conventional Arts 10 and11 mentioned above, there is another problem that the sensitivity is lowwhen detecting the foreign matters upon the wafer surface, on which atransparent thin film is formed.

A first object, according to the present invention, for dissolving suchthe problem(s) as was mentioned above, is to provide a defectsinspecting apparatus and a method thereof, enabling to make inspectionat high sensitivity and further at high speed, about the defects, suchas, fine or microscopic foreign matters and/or scratches, etc., of alevel 0.1 μm, upon a substrate of inspection target, such as, a wafer,for example, having circuit patterns formed thereon, as well as, theinspection target substrate, on a surface of which the transparent thinfilm(s) is/are formed.

Also, a second object is, according to the present invention, toprovided a defects inspecting apparatus and a method thereof, enablingto make an inspection about the foreign matters or defects, at highsensitivity, even in an area or region where the pattern density ishigh.

Also, a third object is, according to the present invention, to provideda defects inspecting apparatus and a method thereof, enabling to make aninspection about the foreign matters, short-circuiting between thewiring patterns, or thin film-like defects, at high sensitivity.

And further, a fourth object is, according to the present invention, toprovide a defects inspecting apparatus and a method thereof, enablingclassification of the foreign matters and defects existing upon theinspection target substrate.

For accomplishing the object(s) mentioned above, according to thepresent invention, first there is provided a defects inspectingapparatus, comprising: a scanning stage for running into a predetermineddirection while mounting an inspection target substrate thereon; anillumination optic system for irradiating an illumination light beamupon a surface of said inspection target substrate at a predeterminedangle inclined thereto; a detection optic system including, anupper-directed detection optic system, having an objection lens forcondensing upper-directed reflected/diffracted lights reflected and/ordiffracted upwards from said inspection target substrate, anupper-directed image-forming optic system for forming an image of theupper-directed reflected/diffracted lights condensed through saidobjection lens, and an upper-directed photo-detector for receiving theimage of the upper-directed reflected/diffracted lights, which is formedthrough said upper-directed image-forming optic system, and therebyconverting into an upper-directed image signal, and a side-directeddetection optic system, having a side-directed image-forming opticsystem for forming an image through condensing side-directedreflected/diffracted lights emitted from said inspection targetsubstrate into a direction inclined so as to flatly intersect saidillumination light beam, and a side-directed photo-detector forreceiving an image of the side-directed reflected/diffracted lights,which is formed through said side-directed image-forming optic system;an A/D converter for converting the upper-directed image signal obtainedfrom the upper-directed photo-detector of said detection optic systeminto an upper-directed digital image signal, and for converting theside-directed image signal obtained from said side-directedphoto-detector into a side-directed digital image signal; and a signalprocessing system for detecting defects upon basis of each of thedigital signals converted within said A/D converter.

Also, according to the present invention, said illumination light beamis made to be a slit-like beam of lights in about parallel with alongitudinal direction thereof, as an illumination condition upon saidinspection target substrate, and nearly normal to the running directionof said scanning stage in the longitudinal direction thereof, withinsaid illumination optic system.

Also, according to the present invention, the upper-directed detectionoptic system of said detection optic system has a space filter forshielding at least repetitive lights of circuit patterns lying on theinspection target substrate, and repetitive light shielding pattern ofthe space filter can be set up, automatically, in sizes andconfigurations thereof. Also, according to the present invention, amagnifying power of said image-forming optic system is variable, withinthe upper-directed detection optic system of said detection opticsystem.

Also, according to the present invention, said upper-directed digitalimage signal is merged by vicinity pixels, and detection is made uponthe defects upon basis of said image signal merged, within said signalprocessing system. And, also according to the present invention, saidsignal processing system further comprises a classifying means forclassifying said defects detected into different categories. Further,according to the present invention, said signal processing system has aclassifying means for classifying the category of the defects, from theeach digital image signal, which is converted in said A/D converter. Andfurther, according to the present invention, said signal processingsystem further comprises a classifying means for classifying saiddefects detected into different categories. Also, according to thepresent invention, said signal processing system further comprises asize measuring means for measuring sizes of said defects detected.

Also, according to the present invention, the defects inspectingapparatus, as described in the above, further comprising an opticalmicroscope for observing an optical image upon said inspection target.And, according to the present invention, an area or a mark indicative ofcoordinates of the defects detected by said signal processing systemupon a screen observed on said optical microscope.

Also, according to the present invention, said illumination light beamis exchangeable between a high-inclination angle and a low-inclinationangle with respect to the surface of said inspection target substratewithin said illumination optic system; and further comprising: a signalprocessing system, having a defects detection processing portion fordetecting the defects upon basis of the digital image signals, which areconverted within said A/D converter portion when illumination is made atthe high-inclination angle and at the low-inclination angle within saidillumination optic system, a characteristic-quantity calculator portionfor calculating characteristic quantities, about the defects detectedfrom said defects detection processor portion, and an integrationprocessor portion for obtaining the characteristic quantities about thedefects, on which coincidence can be considered between the defectsdetected from said defects detection processor portion when theillumination is made at the high-inclination angle and the defectsdetected from said defects detection processor portion when theillumination is made at the low-inclination angle, and for classifyingthe category of the defects upon basis of said characteristic quantitiesobtained.

Also, according to the present invention, for accomplishing theabove-mentioned objects, there is further provided a defects inspectingapparatus, comprising: a scanning stage for running into a predetermineddirection while mounting an inspection target substrate thereon; anillumination optic system for irradiating an illumination spot upon asurface of said inspection target substrate, scanning it into adirection perpendicular to the running direction of said scanning stage;a detecting optic system, having an image-forming optic system forcondensing reflected/scattered lights, which are generated from saidinspection target substrate due to scanning of the illumination spotirradiated within said illumination optic system, and for forming animage thereof, plural numbers of optical fibers receiving lights of theimage of reflected/scattered lights, which is formed said image-formingoptic system due to scanning of the illumination spot, and thereby forguiding, and photomultiplier tubes receiving an optical image due to thescanning of the illumination spot, guided by said plural numbers ofoptical fibers, and for converting it into a signal; and a signalprocessing system for converting the signal obtained from each of saidphotomultiplier tubes into a digital signal, and for detecting defectsupon basis of said digital signal converted.

Also, according to the present invention, for accomplishing the objectsmentioned above, there is further provided a defects inspectingapparatus, comprising: a scanning stage for running into a predetermineddirection while mounting an inspection target substrate thereon; anillumination optic system, having plural numbers of optical modulatorsfor modulating each of plural number of illumination light beams byfrequencies, differing from each other, an optical deflector fordeflecting the plural numbers of illumination light beams, which aremodulate through said plural numbers of optical modulators, into adirection about normal to the running direction of said scanning stage,and a condenser optic system for condensing the plural numbers ofillumination light beams, which are deflected by said deflector, upon asurface of said inspection target substrate in a form of plural numbersof illumination spots, thereby for irradiating; a detecting opticsystem, having an image-forming optic system for condensingreflected/scattered lights, which are generated from said inspectiontarget substrate due to scanning of the plural numbers of illuminationspot irradiated within said illumination optic system, and for formingan image thereof, a photo-detector for receiving lights of the image ofreflected/scattered lights, which is formed said image-forming opticsystem due to scanning of the plural numbers of illumination spots, andfor converting it into a signal; and a signal processing system, havingplural numbers of synchronization detection circuits for extractingcomponents corresponding to frequencies, each being modulated in each ofsaid optical modulators, from the signal converted within thephoto-detector of said detection optic system, and for detecting defectsupon basis of signals extracted from said plural numbers ofsynchronization detection circuits, as well as, a method thereof.

Also, according to the present invention, said photo-detector comprisesoptical fibers for guiding the image of reflected/scattered lights dueto the scanning of the plural numbers of illumination spots receivedthereupon, and photomultiplier tubes, receiving the optical image due tothe scanning of the plural numbers of illumination spots, which areguided through said optical fibers, and for converting it into a signal.

And, further, according to the present invention, for accomplishing theobjects mentioned above, there is provided a defects inspecting method,comprising the followings steps of: a first step for irradiating anillumination light beam upon a surface of an inspection targetsubstrate, having circuit patterns thereon, by an illumination opticsystem, condensing reflected/scattered lights generated from saidinspection target substrate irradiated through an objection lens, so asto form an image thereof through an image-forming system, receiving thereflected/scattered lights upon an upper-directed photo-detector, so asto convert into a first image signal, and thereby detecting defectslying on the surface of said inspection target, having the circuitpatters thereon, upon basis of said first digital image signalconverted; and a second step for irradiating illumination light beamupon a surface of a transparent film on the inspection target substratethrough said illumination optic system at a predetermined inclinationangle thereto, condensing reflected/scattered lights generated from saidinspection target substrate irradiated from a direction inclined so thatit flatly intersect said illumination direction, by means of theimage-forming optic system so as to form an image thereof, receivingsaid reflected/scattered lights forming the image thereof upon aphoto-detector, so as to convert it into a second image signal, andthereby detecting defects lying on the surface of the transparent filmon said inspection target substrate upon basis of said second digitalimage signal converted.

As was explained in the above, according to the present invention, it ispossible to obtain an effect of enabling an inspection about thedefects, such as, fine or microscopic foreign matters and/or scratches,etc., of 0.1 μm on a level thereof, upon an inspection target substrate,on the surface of which a transparent film is formed, and/or aninspection target substrate, on which repetitive patterns andnon-repetitive patterns are mixed with, at high sensitivity and also athigh speed.

And, according to the present invention, it is also possible to obtainan effect of enabling an inspection about, not only the defects, suchas, foreign matters and/or scratches or the like, of 0.1 μm on a levelthereof, but also defects, such as, caused due to foreign mattersshort-circuiting between wiring patterns, and/or the film-like foreignmatters, in particular, upon the inspection target substrate, on whichrepetitive patterns and non-repetitive patterns are mixed with, at highsensitivity and also at high speed.

Further, according to the present invention, it is also possible toobtain an effect of enabling classification of the defects, such as,foreign matters, etc., which are detected, and also measurement on sizesthereof.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

Those and other objects, features and advantages of the presentinvention will become more readily apparent from the following detaileddescription, when taken in conjunction with the accompanying drawingswherein:

FIG. 1 is a brief structure view for showing an embodiment of thedefects inspecting apparatus, according to the present invention;

FIGS. 2( a) and 2(b) are views for showing an illumination optic systemshown in FIG. 1; in particular, FIG. 2( a) is a front view thereof andFIG. 2( b) a perspective view for showing the illumination optic system,as a whole;

FIG. 3 is a plan view for showing the entire of illumination opticsystem, which is shown in FIG. 1;

FIGS. 4( a) through 4(c) are views for showing a method of irradiatingfour (4) illumination light beams; in particular, FIG. 4( a) shows theillumination method, with using a lens having a conical curved surface,and FIGS. 3( b) and 3(c) the illumination with using a cylindrical lenstherein;

FIG. 5 is a view for explaining about a condition where it is difficultto detect the defects lying between wiring patterns, in particular, whenirradiating the illumination light beams 220 and 230 thereupon;

FIG. 6 is a view for explaining about a condition where scattered lightsare generated, in particular, when irradiating an oblique illuminationlight beam 250 upon a transparent film;

FIGS. 7( a) and 7(b) are views for explaining about the variableoperation of an optic system, being variable in magnification powerthereof, which is shown in FIG. 1;

FIGS. 8( a) to 8(c) are views for explaining about automatic setting ofshading patterns within a space filter;

FIGS. 9( a) and 9(b) are views for showing an example, having an opticsystem of protection from blooming within an upper-directed detectionoptic system;

FIGS. 10( a) and 10(b) are views for showing an example of applyingphoto-multiplier tubes, as a photo-detector;

FIG. 11 is a brief structural view, for showing an embodiment of aside-directed illumination optic system and a side-directed detectionoptic system, according to the present invention;

FIGS. 12( a) to 12(c) are views for explaining an embodiment of thephoto-detector, being constructed with plural numbers ofphoto-multiplier tubes, for scanning an illumination spot, within theoptic system shown in FIG. 11;

FIG. 13 is a brief structural view for showing other embodiment of theillumination system and the detection optic system, according to thepresent invention;

FIG. 14 is a view for showing the detailed structures of a signalprocessing system, according to the present invention;

FIG. 15 is the structural view for showing a pixel merge circuit shownin FIG. 14;

FIG. 16 is the structural view for showing a foreign-matter detectionprocessor portion shown in FIG. 14;

FIG. 17 is a view for explaining about a method, for classifyingdefects, including the foreign matters, etc., for example;

FIG. 18 is a view for showing an example of displaying a result ofinspection, in particular, when classifying the defects, including theforeign matters, etc., for example;

FIGS. 19( a) and 19(b) are views for explaining a method of measuringsize of the defects, including the foreign matters, etc., for example;

FIG. 20 is a view for explaining about other embodiment, in particular,relating to the method for calculating out an amount of the scatteredlights from the defects, including the foreign matters, etc., forexample;

FIG. 21 a view for showing a sequence, according to other embodiment, inparticular, relating to classification of the defects, including theforeign matters, etc., for example;

FIGS. 22( a) and 22(b) show classification graphs to be used in theclassification of defects, including the foreign matters, etc., forexample;

FIG. 23 is a view for showing a sequence, according to further otherembodiment, in particular, relating to classification of defects,including the foreign matters, etc., for example;

FIG. 24 is a view for explaining about the method for classifying thedefects, including the foreign matters, etc., from plural kinds ofcharacteristic quantities thereof;

FIGS. 25( a) to 25(c) are views for explaining about a method forsetting up boundaries for the classification;

FIG. 26 is a view for showing an example of display when displaying arate of classification;

FIG. 27 is a view for showing an example of display when showing aresult of classification on the defects, including the foreign matters,etc., showing a result of measurement of sizes thereof, together;

FIG. 28 is a view for showing an example of display when showing aresult of measuring sizes of the defects, including the foreign matters,etc., while showing an observed image of the defects or the foreignmatters, together;

FIG. 29 is a view for showing an example, for displaying a ratio ofcorrectness in the classification of defects, including the foreignmatters, etc., upon a result of inspection thereof;

FIG. 30 is a view for showing a sequence for setting up an inspectioncondition, with the defects inspecting apparatus, according to thepresent invention;

FIG. 31 is a view for explaining a screen for use of setup of an opticalcondition;

FIG. 32 is a view for explaining a screen for use of setup of aninspection condition;

FIG. 33 is a view for showing the brief structure of an embodiment, onwhich an observatory optic microscope is equipped with, according to thepresent invention; and

FIG. 34 is a view for showing a screen, which can be observed throughthe observatory optic microscope shown in FIG. 33.

BEST EMBODIMENT FOR PRACTICING THE INVENTION

Hereinafter, embodiments according to the present invention will befully explained, by referring to the attached drawings.

A defects inspecting apparatus, according to the present invention,enables to make an inspection about various kinds of defects, such as,foreign matters, pattern defects and/or micro-scratches, etc., forexample, on a substrate to be inspected, including, a wafer or the like,of various kinds of products and on various kinds of manufacturingprocesses thereof, further including fine ones and large ones, at highsensitivity and at high speed. For such purposes, within the defectsinspection apparatus according to the present invention, as is shown inFIG. 1, it is characterized that an irradiation angle α of a slit-likebeam 201, which is irradiated by an illumination optic system 10, ismade variable depending on an object to be inspected (i.e., aninspection target), and also that the magnifying power of a detectionoptic system 200 is made variable, while disposing the detection opticsystem 200 so that the surface of the inspection target and thelight-receiving surface of a detector 26 are in a relationship ofimage-forming; thereby, fitting a size of detecting pixel to that of thedefects to be inspected.

Further, the defects inspecting apparatus, according to the presentinvention, has also a function of classifying the defects upon basis ofthe difference between scattered lights, which can be obtained from thedefects, through different irradiation angles of the illuminationlights, in the form of characteristic amounts or quantities, forexample.

Next, explanation will be given about the details of an embodiment ofthe defects inspecting apparatus, according to the present invention. Inthe embodiment mentioned below, although explanation will be givenabout, in particular, in a case when it is applied into an inspection ofsmall/large foreign matters and/or pattern defects and/ormicro-scratches, etc., on a semiconductor wafer; however, it can be alsoapplied onto a photo-mask, a TFT (Thin Film Transistor), PDP (PlasmaDisplay Panel), etc., but should not be limited only to thesemiconductor wafer.

By the way, the defects inspecting apparatus, according to the presentinvention, comprises: a conveyer system 30, having X, Y and Z stages 31,32, 33, and 34 for mounting thereon and moving a substrate 1, i.e., aninspection target, such as, a wafer or the like, which can be obtainedfrom various kinds of products and/or various kinds of manufacturingprocesses, and a controller 35, as is shown in FIG. 1; an illuminationoptic system 10 for making illumination upon the substrate 1, i.e., theinspection target, from plural oblique directions through lenses,mirrors, etc., after expanding a light beam emitted from a laser-lightsource 11 up to a certain size through a beam enlarging optic system 16;a detection optic system 200, being constructed with an objection lens21, a space filter 22, an image-forming optic system 23, a group ofoptic filters 24 (which will be shown in FIG. 7( a)), and aphoto-detector 26, such as, of TDI image sensors or the like, forexample, and further having a magnification-variable detection opticsystem 20 for detecting reflected/diffracted lights (or, scatteredlight) reflected and/or diffracted from a region where illumination ismade by the illumination optic system 10, as well as, a side-directeddetection optic system 600 having an image-forming optic system 630 anda photo-detector 640, etc.; a signal processing system 40; and a totalcontroller portion 50 for setting up inspection conditions and forcontrolling the illumination optic system 10, the detection optic system200 including the magnification-variable detection optic system 20,etc., the conveyer system 30, the signal processing system 40, anobservatory optic system 60, and so on. The total controller portion 50is equipped with an input/output means 51 (including a keyboard and/or anetwork, too), a display means 52, and a memory portion 53.

Further, this inspecting apparatus of foreign matters is provided withan automatic focus controller system (not shown in figures), so that asurface image of the wafer can be formed upon light-receiving surfacesof the photo-detectors 26 and 640.

[Illumination Optic System 10]

The present inspecting apparatus is so configured in the structure, thatillumination can be made upon the surface of the substrate 1, i.e., theinspection target, from plural numbers of directions. Within thestructure of this illumination optic system 10, the light L0 emittedfrom the laser-light source is irradiated upon the wafer (i.e., theinspection target substrate) mounted on the sample-mounting base 34,from one (1) or more directions (for example, four (4) directions inFIG. 3), flatly, in the form of a slit-like beam 201, through the beamenlarging optic system 16, which is constructed with a concave lens 12and a convex lens 13, etc., a conical surface lens 14 for forming theslit-like light beam, and a mirror 15, as is shown in FIGS. 2( a) and2(b). It is also configured such that, in this instance, a longitudinaldirection of the slit-like beam 201 is directed into the direction ofthe alignment of chips. The reason of forming the illumination lightinto the slit-like beam 201 lies in that light-receiving elementsaligned can collectively detect the scattered lights from the foreignmatters and/or the defects, once, which are generated due to theillumination, and thereby achieving high speed of inspection. Namely, asis shown in FIG. 3, the slit-like beam 201, being irradiated upon thewafer 1, on which the chips are aligned directing into the scanningdirections of the X stage 31 and the Y stage 32, has a shape of beingnarrow in the scanning direction X of the X stage 31, but wide in the Ydirection perpendicular to that (i.e., the scanning direction of the Ystage 32). And, this slit-like beam 201 is irradiated, so that an imageof the light source can be formed in the X direction while it comes tobe parallel light in the Y direction, due to the provision of, such as,a cylindrical lens within an optical path. However, the details of thisillumination directing into three (3) directions is described inJapanese Patent Laying-Open No. 2000-105203, for example.

By the way, the reason of directing the longitudinal direction of theslit-like beam 201 into the aligning direction of chips, with respect tothe wafer 1, lies in that comparison can be made, easily, between thechips on an image signal, while keeping pixel alignments of thephoto-detector 26 and moving direction of the X stage 31 in parallelwith, and also that calculation can be made easily, about the positionalcoordinates of the foreign matters; thereby, as a result, achieving aneffect of enabling the inspection of the foreign matters at high speed.

In particular, the conical surface lens 14 (224, 234) is necessary fordirecting the illumination of the slit-like beam 201 of illuminationlight beams 220 and 230, which are irradiated from the directioninclined by φ with respect to the Y direction, in the plane surfacethereof, into the direction of alignment of the chips 202 on the wafer1, and also for forming it to be orthogonal to the scanning direction Xof the X stage 31. This conical surface lens 14 (224, 234) is a lens,being different in the focal distances at positions on the longitudinaldirection thereof, and changing the focal distances, linearly; i.e., theradius of curvature is continuously changed in the longitudinaldirection thereof. With such structure thereof, if irradiating from anoblique direction (satisfying an inclination of both, an angle α and adirection φ), as is shown in FIG. 4( a), an illumination can be obtainedby the slit-like beam 201, which is reduced in the X direction and iscollimated in the Y direction thereof. Further, it has such thestructure that an illumination angle α can be changed depending uponkinds of the foreign matters and/or defects, for example, as being theinspection target on the substrate 1 to be inspected, by exchanging themirror 15 (225, 235) and also a mirror 702, mechanically, as shown inFIG. 2( a), or by changing an angle of one (1) piece of the mirror 15upon basis of an instruction from the total controller portion 50 withan aid of a rotation means not shown in figures. In FIG. 2( a), thelaser illumination is irradiated at an illumination point or position701 by means of the mirror 15. In case of changing the illuminationangel α, it is enough to replace the mirror 15 with the mirror 702,which is different from the mirror 15 in the angle thereof, and furthermove that mirror 702 for irradiating the laser light at the illuminationpoint 701 into the Z direction. In this instance, since the distance ischanged from the convex lens 13 up to the illumination point 701, thenthere is necessity of changing the position of the convex lens 13 and/orchanging it to a convex lens having different focal distance.

Further, upon illumination made from the X direction and the Ydirection, as is shown in FIGS. 4( b) and 4(c), it is possible to formthe slit-like beam 201 by means of cylindrical lenses 244 and 255.

As was explained in the above, the construction is so made, that theslit-like beam 201 has an illumination area or region of covering overpixel alignments 203 of the photo-detectors 26 and 640, in any case ofthe illumination angles, and that the slit-like beam 201 is coincidentwith on the wafer, upon illumination irradiated from any direction.

With this, it is possible to obtain an illumination having parallelrays, and also at the angel in vicinity of φ=45 degree. In particular,converting the slit-like beam 201 into the parallel rays into the Ydirection brings about that the diffracted light patterns generated fromcircuit patterns is blocked or shielded by means of the space filter 22.

However, since description is given about the method for manufacturingthe conical surface lens 14, in Japanese Patent Laying-Open No.2000-10520 (2000), for example; therefore, it will be omitted herein.

Next, explanation will be made about an embodiment of changing theillumination angle α and the illumination direction φ of theillumination optic system 10 depending upon the substrate, as theinspection target, which is mounted on the stage, upon basis of aninstruction from the total controller portion 50. By the way, the reasonof forming the slit-like beam 201 on the wafer 1 by plural numbers ofthe illumination angles is for dealing with the detections of varioustypes of foreign matters and/or defects, which are generated on thesurface of the wafer 1. Thus, detection is targeted upon the patterndefects and/or foreign matters having a low height. Since theillumination angle α increases in an amount of reflected/diffractedlights from the circuit patterns when it comes up to high angle, therebylowering the S/N ratio, therefore an optimal value should be applied,which can be obtained experimentally. As an example, if trying to detectmainly the foreign matters having low height on the surface of wafer, itis preferable that the illumination angle α be set to be small, such as,from 1 degree up to 5 degree, for example. By setting the illuminationangle α to be small, in this manner, the S/N ratio can be improved ofthe foreign matters upon the most surface of the wafer. Also, whentrying to detect mainly the foreign matters between wiring patternsand/or the pattern defects, during the wiring process, it is preferableto set the illumination angle large; however, from a viewpoint of arelationship of the S/N ratio between the circuit patterns and theforeign matters, it is desirable to be set from 45 degree to 55 degree,approximately. Also, if there is correspondence between themanufacturing processes (such as, an etching process and a CMP process,for example) of the inspection target and the foreign matters and/or thedefects to be detected, it is also possible to determine on whichillumination should be set up, in advance, within an inspection recipe.Further, for detecting the foreign matters and the pattern defects onthe wafer surface mentioned above, it is also possible to set up theillumination angle at a value defined between those angles mentionedabove.

Further, regarding the illumination direction φ, in case of the wiringprocess, for example, when the illumination light beams 220 and 230 areirradiated from the direction in vicinity of 45 degree of φ, since theremay be generated a situation where no scattering light diffracted can beobtained from the foreign matters and/or the defects 501 lying betweenthe wiring patters 500, as is shown in FIG. 5, therefore, it ispreferable to select the illumination 240 from the directions inparallel with the aligning direction of patterns of an illuminationcircuit (for example, x direction). In other words, fitting the paralleldirection of the illumination light 240 to the direction of wiringpatterns 500 enables easy detection of the foreign matters and/ordefects between the wiring patterns 500. Also, in a case if the circuitpatterns on the wafer 1 include a contact hole or a capacitor, etc.,other than the wiring patterns, since there is no specific directionalproperty (or, orientation), it is preferable that the illumination lightbeams 220 and 230 are irradiated onto the chip from a direction of φ invicinity of 45 degree.

Further, detailed description will be made about the illumination opticsystem 10.

First, explanation will be made on a method of changing the illuminationdirection φ. FIG. 2( b) and FIG. 3 are plane views; in particular, inthe case where four (4) sets of the illumination optic systems 10 areconstructed by using only one (1) lager light-source 11. A branchingoptical element 218, being built up with a mirror, a prism, and so on,transmits the laser light L0 emitted from the laser light-sourcetherethrough, or reflects it thereupon, thereby to guide it into three(3) directions, through movement in the position thereof in the Ydirection. A first laser light L1 penetrating through the branchingoptical element 218 is separated into a penetrating light and areflected light through a branching optical element 221, such as, a halfprism or the like (for example, a polarization beam splitter), whereinfrom the light penetrating therethrough can be obtained the illuminationlight beam 230, having the inclination angle of α and the directioninclined by φ from the Y axis, by reflecting it upon the mirror 235,again, via a mirror 231, an optic system 232 for adjusting the beamdiameter, a mirror 233 and the conical surface lens 234 shown in FIG. 4(a), while from the light reflected upon the other branching opticalsystem 221 can be obtained the illumination light beam 220, having theinclination angle of α and the direction inclined by φ from the Y axis,by reflecting it upon the mirror 225, again, via an optic system 222 foradjusting the beam diameter, a mirror 223 and the conical surface lens224 shown in FIG. 4( a). However, the beam-diameter adjusting opticalsystems 222 and 232 are provided for adjusting the beam diameters of thelaser beams, which are incident upon the conical surface lenses 224 and234, so that the slit-like beam 201 can be obtained being equal in thesize, which is irradiated upon the wafer 1. Also with provision of amirror 260 in the place of the half-prism, as being the branching opticelement 221, it is possible to obtain an illumination from one side.Also, with insertion of wave plates (e.g., λ/2 plates) 226 and 236behind the branching optic element (for example, the polarization beamsplitter) 221, it enables to align the polarization direction of thelaser lights to be irradiated thereupon.

By the way, after passing through the beam-diameter adjusting opticalelement 241, the second laser light L2 reflected upon the branchingoptical system 218 is further reflected upon mirrors 242 and 243, to beincident upon the cylindrical lens 244, as is shown in FIG. 4( b), andit can be obtained in the form of the illumination light beam 240,having an angle β inclined from the X direction, through reflectionthereof upon a mirror 245; and, the third laser light L3 reflected uponthe branching optical system 218 is further reflected upon mirrors 251,253 and 254, to be incident upon the cylindrical lens 255, as is shownin FIG. 4( c), and it can be obtained in the form of the illuminationlight beam 250, having an angle γ inclined from the Y direction, throughreflection thereof upon a mirror 256. With the illumination light beam240 mentioned above, for example, in the wiring process, it is possibleto fit the direction of illumination (i.e., the X direction) thereto, inparticular, in the case where the wiring patters formed on the wafer areparallel to the X and Y directions in a large number thereof, therebyenabling an easy detection of the foreign matters and defects 501 lyingbetween the wiring patterns 500, as shown in FIG. 5. For the wiringpatterns aligning into the Y direction, it is enough to rotate the wafer1 around, by an angle of 90 degree. And, with the inclination angle β ofthe illumination light beam 240, it may be set at the middle angle orthe high angle mentioned above, from a viewpoint of detection of theforeign matters and/or defects lying between the wiring patters. It isalso possible to make the inclination angle β exchangeable, in thesimilar manner to the angle α. In this manner, it is possible to makethe mirror 245 small in sizes thereof, from the fact that theillumination light can be focused to be narrow in the X direction bymeans of the cylindrical lens 244, when it is irradiated from the Xdirection, and as a result thereof, it is also possible to obtain theillumination at the angle, even being high, by putting that mirror 245into between around the object lens 21 and the wafer 1.

In particular, according to the present invention, as will be mentionedlater by referring to FIG. 6, the illumination is made at theinclination angle γ from the longitudinal direction (i.e., the Ydirection) of the slit-like beam 201, by means of the illumination lightbeam 250 upon basis of the third laser beam L3, as was mentioned above,so as to detect fine or microscopic foreign matters and/or scratches ona transparent film (such as, an oxidation file) 800, upon which the CMP(Chemical Mechanical Polishing) process is treated, from an obliquedirection ω intersecting the Y direction, so as to lesson receiving ofthe ill influences due to the lights scattered from background patterns801. With this inclination angle γ of the illumination light beam 250,it is preferable to be set from 5 degree to 10 degree, approximately, atan angle relatively low, from a viewpoint of detection of the fineforeign matters and/or scratches or the like, on the oxidation film 800.By the way, when using a cylindrical lens 255 having a uniform focaldistance therein, the slit-like beam 201 comes to be drum-like, beingnarrowed in width at a center thereof. However, it is possible to obtainthe slit-like beam, not being narrowed at the center, by exchanging thefocal distances of the cylindrical lens 255, so as to be fit to theinclination angle γ.

Herein, when trying to obtain an illumination only from the illuminationlight beam 240, it can be achieved by exchanging the mirror portionwithin the branching optical element 218. Also, when trying to obtainthe illuminating from two (2) directions by means of the illuminationlight beams 220 and 230, it can be achieved through taking out thebranching optical system 218, or replacing it by a transmitting portion.

Further, as the laser light-source 11, it is desirable to apply thesecond high-frequency SHG of YAG laser of a high output, having awavelength 532 nm, for example, by taking the facts into theconsideration, that it enables the inspection with high sensitivity andthat it is cheap in the maintenance cost; however, there is not always anecessity that the wavelength of 532 nm, but it may also be a lightsource, such as, a UV (ultraviolet) laser, a far ultraviolet (FUV)laser, a vacuum UV (ultraviolet) laser, an Ar laser, a nitrogen laser, aHe—Cd laser, an excimer laser, or a semiconductor laser, etc. As anadvantage of applying each of those lasers, if the laser wavelength isshortened, since the resolution of an image detected can be increased,therefore it is possible to achieve the inspection thereof with highsensitivity. However, if applying the wavelength of about 0.34 μm, thenthe NA of the objection lens 21 be 0.4 or more or less, or if applyingthe wavelength of about 0.17 μm, then the NA of the objection lens 21comes to be 0.2 or more or less; thereby enabling an improvement uponthe detection sensitivity since the much of diffracted lights can beincident upon the objection lens 21. Also, with applying of thesemiconductor laser or the like, there can be obtained an apparatussmall-sized and of low-costs.

[Detection Optic System 200]

Firstly, explanation will be given about the magnification-variabledetection optic system (an upper-directed detection optic system) 20 ofthe detection optic system 200, by referring to FIGS. 1, 7 and FIG. 8.The magnification-variable detection optic system (the upper-directeddetection optic system) 20 is constructed in such that, the lightsreflected and/or diffracted from the inspection target substrate 1, suchas, the wafer, etc., can be detected upon the photo-detector 26, suchas, the TDI image sensors or the like, through the objection lens 21,the space filter 22, the image-forming optic system (amagnification-variable image-forming optic system) 23, and the opticfilter group 24 having a ND filter 24 a and a polarization plate 24 b,etc.

The space filter 22 has a function of passing the scattered lightstherethrough, which are generated from the foreign matters, whileshielding the lights of a Fourier conversion image due to the lightsreflected and/or diffracted from the repetitive patterns on the wafer 1,and it is disposed within a space frequency area of the objection lens21, i.e., an image-forming point of the Fourier conversion(corresponding to an exit pupil).

Next, explanation will be made about an automatic setting of the spacefilter 22 of using a pupil observatory optic system 70, by referring toFIG. 1 and FIGS. 8( a)-8(c). Namely, the space filter 22 is so adjustedthat it picks up an image, for example, of the lights reflected and/ordiffracted from the repetitive diffraction patterns 902 at the positionwhere the image of Fourier conversion is formed, as is shown in FIG. 8(a), by means of the pupil observatory optic system 70 including a mirror90, which can be escaped from during the inspection operation, aprojection lens 91, a TV camera 92, on the optical path of the detectionoptic system 200, and it obtains an image 904 having no bright spot ofthe lights reflected and/or diffracted from the circuit patterns at theimage-forming position of the Fourier conversion, as is shown in FIG. 8(c), by changing an interval or pitch “p” of a light shielding portion903, which is provided at the position where the Fourier conversion canbe formed, through a mechanism not shown figures, as is described inJapanese Patent Laying-Open No. Hei 5-218163 (1993), for example. Thoseare automatically set up through adjustment on the pitch “p” and/orrotation direction of the light shielding portion 903 within the spacefilter 22, upon basis of an instruction from the total controllerportion 50 processing the signals from the TV camera 92 within thesignal processing system 40. However, without applying such the lightshielding plate therein, as was mentioned above, but it may be madethrough forming a light shielding portion reduced in sizes, such as,through forming whites and blacks in reverse on a transparent substrateupon basis of the signals from the TV camera 92.

The present inspecting apparatus has such a function of conducting thedefect inspection at a high speed, and also of conducting the inspectionwith high sensitivity, but at a low speed. Namely, the inspection can beexecuted with high sensitivity upon an inspection target or an areawhere the circuit patters are manufactured at high density, since animage signal of high resolution can be obtained with increasing up themagnification of the detection optic system. Also, the high-speedinspection can be achieved by lowering the magnification down, upon aninspection target or an area where the circuit patters are manufacturedat low density, while keeping the high sensitivity.

With this, it is possible to optimize the sizes of the foreign mattersto be detected, as well as, the size of the detecting pixels; therebybringing about an effect of eliminating noises other than is those fromthe foreign matters, so as to detect only the lights scattered from theforeign matters, with high efficiency. Namely, with the presentinspection apparatus, the magnification of the detection optic system200 provided above the wafer 1 can be changed with simple structurethereof.

Next, explanation will be made about the operation of changing themagnification of the detection optic system 200, by referring to FIGS.7( a)-7(b). Change of the magnification of the detection optic system200 is executed upon basis of an instruction from the total controllerportion 50. The image-forming optic system (i.e., themagnification-variable image-forming optic system) 23 comprises amovable lenses 401 and 402, a fixed lens 403, and a moving mechanism404, and is characterized in that the magnification of a wafer surfaceformed on the photo-detector 26 can be changed, but without changing thepositions of the objection lens 21 and the space filter 22 when changingthe magnification thereof. Namely, it has the following advantages: evenwhen changing the magnification, but there is no necessity of changingthe relative position between the inspection target substrate 1 and thephoto-detector 26, when changing the magnification; the magnificationcan be changed with the simple structure of a driving or movingmechanism 404 when changing the magnification; and further, there is nonecessity of changing the space filter, since no change is caused onsizes of the Fourier conversion surface.

The magnification M of the magnification-variable detection optic system20 can be calculated out from the equation (1), which will be shownbelow, while assuming that the focal distance 405 of the objection lens21 is f₁ and the focal distance 406 of the image-forming optic system 23f₂, respectively:M=f ₂ /f ₁  (1)

Accordingly, for building up the magnification-variable detection opticsystem 20 to be M in the magnification thereof, since f₁ has a fixedvalue, therefore f₂ is moved to the position where (M/f₁) can besatisfied.

Next, explanation will be given in details of the moving mechanism 404,by referring to FIG. 7( b). This FIG. 7( b) shows the structure forpositioning the movable lenses 401 and 402 at specific positionsthereof, within the moving mechanism 404. However, the moving mechanism404 is also applicable to make a control of positioning of those movablelenses 401 and 402 at arbitrary positions. Also, the moving mechanism404 is constructed with lens holder portions 410 and 420 for the movablelenses 401 and 402, ball screws 412 and 422, and also motors 411 and421. Thus, the movable lens 401, which is held by the lens holderportion 410, and also the lens holder portion 410 move through rotationof the ball screw 412 driven by means of the motor 411, while themovable lens 402, which is held by the lens holder 420, moves throughrotation of the ball screw 422 driven by means of the motor 421,independently, to predetermined positions in the Z direction,respectively.

And, providing the movable portion 415 or 425 on the positioning sensorat an end of the lens holder portion 410 or 420, which holds the movablelens 401 or 402, while providing a detector portion 416 or 426 of thepositing sensor at a stopping position of the movable lens 410 or 420,the motor 411 or 421 is driven, so as to move the lens holder portioninto the Z direction, then the each positioning sensor 416 or 426, beingprovided at a position of the desired magnification, detects the movableportion of the positioning sensor, and thereby achieving the positioningthereof. However, the positioning sensor 440 is a limit sensor for anupper limit in the Z direction, while the positioning sensor 430 a limitsensor for a lower limit in the Z direction. Herein, as such thepositioning sensor mentioned above, there can be considered an opticalor a magnetic sensor to be applied thereto.

Although those operations are conducted upon basis of the instructionfrom the total controller portion 50, but the magnification should beset at, depending upon the pattern density on the inspection targetsubstrate 1, which is mounted on the stages 31-34. For example, when thecircuit pattern has a high density, the high magnification should beselected, to obtain an inspection mode of high sensitivity, but when thecircuit pattern has a low density or there is necessity of a high-speedinspection, then a low magnification should be selected.

Also, as other embodiment of the magnification-variable detection opticsystem 20, in particular when change is not frequently made on themagnification, there can be also considered to exchange a unit, byunitizing the portions of the movable lens as a unit. In this instance,there can be obtained a merit of enabling adjustment and maintenancewith ease.

Next, explanation will be made on the optical filter group 24. The NDfilter 24 a is for use of adjusting an amount of lights detected uponthe photo-detector 26, and then the photo-detector 26 turns into thesaturated state when receiving the reflected lights of high brightnessthereupon; therefore, it cannot detect the foreign matters withstability. This ND filter 24 a is not always necessary when an amount ofirradiation lights can be adjusted within the illumination optic system10; however, with using the ND filter 24 a therein, it is possible toenlarge an adjustable range on an amount of detection lights; therebyenabling an adjustment on the light amount to be the most suitable forvarious inspection targets. For example, an output can be adjusted from1 W up to 100 W with using the laser light source 1, and if preparing afilter of 100% penetration and a filter of 1% penetration, as the NDfilter 24 a, the light amount can be adjusted from 10 mW up to 100 W;therefore, it is possible to adjust the light amount, widely.

The polarization plate 24 b is for use of shielding the polarizationlight components caused due to the lights reflected and/or diffractedfrom the edges of circuit patterns, and passing a part of thepolarization light components therethrough, which are generated from theforeign matters when an illumination is made with polarization lightsthereupon, within the illumination optic system 10.

Next, explanation will be given about the photo-detector 26. Thephoto-detector 26 is an image sensor for receiving the upper-directedlights reflected and/or diffracted, which are condensed by means of theimage-forming optic system 23, and for conducting photoelectricconversion thereupon, and it may be a TV camera, a CCD linear sensor, aTDI sensor, an anti-blooming TDI sensor, or a photo-multiplier tube, forexample.

Herein, as a manner for selecting the photo-detectors 26 and 640, it ispreferable to apply the TV camera or the CCD linear sensor, whenbuilding up a cheap inspection apparatus, and it is preferable to applythe sensor having the TDI (Time Delay Integration) function or thephoto-multiplier tube, when detecting weak or feeble lights with highsensitivity, such as, when detecting the very fine foreign matters, suchas, being less than 0.1 μm, approximately, for example.

Next, explanation will be made about an embodiment for improving dynamicrange within the photo-detector. By the way, difference appears in theintensity between the lights reflected and/or diffracted from thecircuit patterns, depending upon an inspection target area on the wafer.Thus, comparing between a portion of memory cells, on which the circuitpatterns are formed repetitively, and a periphery portion thereof; theintensity is stronger of the lights reflected and/or diffracted fromthat periphery portion. Also, though it is possible to eliminate thelights reflected and/or diffracted from the circuit patterns of thememory cell portion, much more, by means of the space filter 22, forexample; however, it is difficult to eliminate that generated from theperiphery portion or the like, since there exist various patternstherein, by means of the space filter 22. Because of being under suchthe situation, if the dynamic range comes to be large on the lightsreceived upon the photo-detector 26 when the inspection target areareaches to the periphery portion or the like, in other words, in a casewhen such the lights are incident upon the sensor that it is saturated,it is preferable to apply a sensor added an anti-blooming functionthereto; however, as is described, for example, in Japanese PatentLaying-Open No. 2000-105203 (2000), a beam splitter 100, being differentin the transmissivity (for example, 99%) and the reflectivity (forexample, 1%) thereof, may be disposed at the position of the mirror 90,for example, on the optical path within the detection optic system 20,as is shown in FIG. 9( a), as well as, providing the photo-detectors 26and 101 on the respective optical paths. Of course, it is also possibleto build up the above-mentioned beam splitter 100 with a half-mirror,with provision of the ND filters between that half-mirror and thephoto-detectors 26 and 101, separately; thereby, differing an amount oftransmitted lights from each other. In this instance, when such stronglights generated from the periphery portion or the like are incidentupon the sensor that it is saturated, then the defects, such as, theforeign matters, may be detected upon basis of an image signal, whichcan be obtained by attenuating or damping an amount of lights receivedfrom the photo-detector 101, but with those generated from the memorycell portion, the defects, such as, the foreign matters, may be detectedupon basis of the image signal, which can be obtained from thephoto-detector 26. However, as a manner for detecting the defects, suchas, the foreign matters, upon basis of the image signal (an image signalof enhancing the background, relatively), which can be obtained from thephoto-detector 101, there is known a method of extracting a signalindicative of the defects, such as, the foreign matters, etc., which aregenerated at random, through eliminating the image signal of thatbackground at the level almost same to that by chip comparison in thesignal processing. With this, it is possible to detect the defects, suchas, the foreign matters, etc., but without conducting the inspection byplural numbers of times, while changing strength of the illumination, inthe areas, not only the memory cell portion, but also the peripheryportion or the like thereof.

Also, when applying the TDI sensor therein, as is shown in FIG. 9( b),there can be considered a case of using an element, on which lines 26′a(26) and 26′b of light receiving portions are formed, being different onstage numbers for taking out signals therefrom, among the lines of lightreceiving elements of 100 stages, for example, as is shown in FIG. 9(b). For example, with the structure of dividing a portion 26′b fortaking out an intensity signal of 1% accumulated on the line oflight-receiving elements of one (1) stage, and other portion 26′b fortaking out an intensity signal of 99% on the lines of light-receivingelements of the remaining 99 stages, the blooming can be prevented frombeing generated even when strong lights are incident thereon, therebyenabling to process the respective output signals through the signalprocessing system 40, in the similar to that mentioned above.

Next, explanation will be made about an embodiment of applying thephoto-multiplier tube therein, by referring to FIG. 10. This FIG. 10shows a sensor of aligning the photo-multiplier tubes in theone-dimensional direction. In this case, since it can be used as aone-dimensional sensor having high sensitivity, therefore it is possibleto make an inspection with high sensitivity. With the structure in thisinstance, as shown in FIG. 10( a), micro-lenses 5002 may be attached ona side of the image-forming optic system 23 of the photo-multipliertubes 5001, thereby detecting the reflected/diffracted lights, which arecondensed within the image-forming optic system 23. Herein, themicro-lenses 5002 have functions of condensing the lights, as is equalto the surfaces thereof on the photo-multiplier tubes 5001. Also, as isshown in FIG. 10( b), optical fibers 5004 may be attached via jigs 5003provided in downstream of the micro-lenses 5002, and further thephoto-multiplier tubes 5001 are attached to output terminals of theoptical fibers 5004, in the structure thereof. In this instance, sincethe diameter of the optical fiber is smaller than that of thephoto-multiplier tube 5001, the sensor pitch can be made smaller thanthat shown in FIG. 10( a); therefore, it is possible to build up asensor having high resolution.

Next, explanation will be made about the side-directed detection opticsystem 600 within the detection optic system 200, by referring to FIGS.1 and 11. Thus, in the inspection of foreign matters, due to highintegration of the semiconductors, there is caused a necessity of makingan inspection also upon a multi-layer wafer, which is increased in trendof the recent years. As is shown in FIG. 6, the multi-layer wafer isproduced through repetition of a process of forming a transparent film(for example, an oxidation film) 800 and forming the circuit patterns onit, upon the surface of the wafer. Then, with an inspection on foreignmatters on the wafer, a need goes up, in particular, for inspecting thedefects 802, such as, very fine foreign matters and/or scratches on thesurface of the transparent film 800.

Basically, by making the illumination angle α small with using theillumination light beams 220 and 230, it is possible to suppress the illinfluences of the lights reflected and/or diffracted by the circuitpatterns from the background 801; however, since much of the scatteringlights, which are generated from the defects due to making theillumination angle α small, come to exit at a low angle in the form of aforward scattering lights, therefore an incident light lowers down to beless, upon the object lens 21 of the detection optic system 200, then itis impossible to detect the defects 802 on the transparent film 800 withstability. Also, if receiving the forward scattering lights at the lowangle, but it means the detection of the regular reflection light, andtherefore it is impossible to detect the defects 802.

Then, according to the present invention, as was mentioned above, thelaser beam L3, which is enlarged on the beam diameter thereof, isirradiated upon the surface of the wafer 1 through the cylindrical lens255, at the low illumination angle γ (approximately, from 5 degree up to10 degree, for example), in the form of the illumination light beam 250,as shown in FIG. 11, and thereby forming the slit-like beam 201 havingthe longitudinal direction directed into the Y direction. However, as isshown in FIGS. 1 and 2( b), it is preferable to provide the cylindricallens 225 in front of the mirror 256 on the optical path of theillumination light. And, the side-directed detection optic system 600 isdisposed, with respect to the illumination light beam 250 generated fromthe fine foreign matters and/or the scratches or the like 802, lying onthe transparent film 800 formed on the surface of the wafer 1, in suchmanner that it can detects mainly the side-directed scattered lightsthereof at a low angle. For that purpose, that side-directed detectionoptic system 600 comprises an image-forming optic system 630 and aphoto-detector 640, each having an optical axis inclined by the lowdetection-angle θ (from 5 degree to 10 degree, approximately) from thedirection intersecting the Y direction by an angle ω (for example, from80 degree to 100 degree, approximately). Then, setup of the intersectionangle ω in the vicinity of 90 degree brings the light-receiving surfaceof the photo-detector 640 to have a relationship of forming an imagethrough the image-forming optic system 630, with respect to theslit-like beam 201, and it further allows setup of a magnifying power ofimage-forming within the image-forming optic system 630, so that thelight-receiving surface of the photo-detector 640 can front on theentire illumination area or region of the slit-like beam 201. Bybringing the side-directed detection optic system 600 into therelationship of forming such the image, at the low angle with respect tothe slit-like beam 201, in this manner, it is possible to prevent illinfluences of lights straying from other than the slit-like beam area;therefore, enabling parallel processing thereof, in the similar mannerto the magnification-variable detection optic system 20, and obtaininghigh-speed of the inspection. Further, the photo-detector 640 can bebuilt up with the TDI sensor or the photo-multiplier tubes, etc., in thesimilar manner to the photo-detector 26.

Also, during the inspecting operation, the surface of the wafer 1 staysat a constant position in the Z direction, while the photo-detector 640is controlled by an automatic focus controller system not shown infigures, so that the light-receiving surface thereof can capture theentire illumination area of the slit-like beam 201. Also, with provisionof the space filter within the optical path of the side-directeddetection optic system 600, it is possible to shield the lightsreflected and/or diffracted from the side of the circuit patters lyingon the background and so on.

Further, with provision of devices on the image-forming optic system630, it is possible to widen the area of the intersection angle ωmentioned above. Also, for the illumination light beam, if theinclination angle α thereof comes down to a low angle, it is possible toapply the illumination light beam 220 therein. In this instance, whatcan be detected by means of the side-directed detection optic system 600is the detection of the scattering lights in the side-front (in thedirection of 135 degree, seeing flatly). Also, when applying theillumination light beam 230 therein, it is sufficient to provide theside-directed detection optic system 600 between the mirrors 245 and225, each of which has no interference between the illumination systems.

As was explained above, with provision of the side-directed detectionoptic system 600 for detecting mainly the side-directed scattered lightsthrough forming it into the slit-like beam 201 at the low angle, it ispossible to detect the defects, such as, the fine foreign matters and/orscratches on the transparent film 800, at high accuracy, but suppressingthe ill influences due to the light reflected from the background.

Also, as is shown in FIG. 12( a), scanning the laser light L3, forexample, at high speed in the Y direction by means of a light deflectingmeans (i.e., a light deflector) 720, so as to obtain high-speed scanningof a spot 701, which is condensed and irradiated upon the surface of thewafer at the low angel γ through the condenser lens 730; thereby formingan image of the side-directed scattered lights generated from thedefects 802, such as, the foreign matters and/or scratches, etc., uponthe light-receiving surface of a distributor means 750, such as, theoptical fibers, through the image-forming lens 740 at the low angle θ;thereby, it is possible to detect that optical image formed uponphoto-electric conversion elements 760 a-760 d, such as, thephoto-multiplier tubes, etc., for example, being guided by means of thedistributor means 750 mentioned above. In the case of this embodiment,those elements attached with the reference numerals 740-760 build up aside-directed detection optic system 600′. In this case, as is shown inFIG. 12( b), forming spot scanning groups 701 a-701 c in plural numbersthereof on the wafer 1 enables to obtain high-speed in the scanning withuse of the photo-multiplier tubes, or the like. Also, with detection ofthe scattered lights generated from each of the scanning spots 701 a-701c due to the defects, as is shown in FIG. 12( c); optical informationguided by the distributor means 750 can be signal-processed in parallel,through picking up on the photo-multiplier tubes 760 a-760 d at aconstant interval, and therefore it is possible to make the inspectionthereof at high speed. As a result of this, it is possible to reduce thenumber of the photo-multiplier tubes, thereby detecting the defects 802,without offset or deflection thereof. Thus, since the detection positionof each of the photo-multiplier tubes is determined in the Y directionon the wafer, by applying the deflection signal of the light deflector720 therein, it is sufficient to detect the signal of the defectsdetected from the each photo-multiplier tube in synchronism with thehigh-speed scanning of the spot 701.

Also, the laser light L3 is divided into plural numbers of laser lights132 a-132 d, by means of a branching means 131 (131 a-131 d), and eachof the laser lights 132 a-132 d is modulated in the intensity thereof,for example, with the frequencies being different from each other withinoptical modulators 133 a-133 d, upon basis of the signals fromoscillators 134 a-134 d. And then, each of those laser lights 135 a-135d, which are modulated in intensity thereof, is reflected upon mirrors136 a-136 d and 137 a-137 d, and further it is deflected into the Ydirection within an optical deflector 138, to be condensed through acondenser lens 139, thereby being irradiated upon the wafer 1 at theinclination angle γ in the form of multi-spots 140 a-140 d. Herein, eachof the optical deflectors gives such an offset onto the deflectionangle, that those spots will not overlap each other, completely, in theY direction. With this can be obtained the multi-spots 140 a-140 d,which are modulated in the intensity thereof with frequencies differentfrom one another and are scanned in the Y direction, entering at theinclination angle γ. On the contrary to this, the side-directeddetection optic system comprises an image-forming lens 141, alight-receiving portion 142, optical fibers 143 connected with thatlight-receiving portion 142, and a photo-multiplier tubes 144. However,it is possible to build up the photo-detector with those, including thelight-receiving portion 142, the optical fibers 143 and thephoto-multiplier tubes 144. Reference numerals 145 a-145 d depictsynchronization detector circuits, each detecting the frequency includedin the signal components outputted from the photo-multiplier tubes 144with an aid of the signals of respective frequencies, which are obtainedfrom the respective oscillators 134 a-134 d and are applied to therespective optical modulators 133 a-133 d; thereby enabling to detect onwhich one of scanning of the spots 140 a-140 d the defects occurs. Thus,the photo-multiplier tubes 144 receive the side-directed scatteringlights from the defects 802 through scanning of the multi-spots;however, with an aid of the signal indicative of the defects, which isdetected from the respective synchronization detector circuits 145 a-145d and outputted therefrom, it is possible to discriminate on whichscanning of the spots 140 a-140 d generates that signal. As a result ofthis, the signal processing system 40 is able to calculate out acoordinate in the Y direction, of the position where the defects aregenerated, upon basis of the deflection signals (corresponding to thescanning signals on the wafer) from a controller circuit 146 forcontrolling the optical deflector 138.

As was explained above, irradiating the lights, each of which ismodulated in intensity with frequencies differing from each other ineach of the optical modulators 133 a-133 d, respectively, for example,and are scanned, in the form of the multi-spots 140 a-140 d, andextracting the signal indicative of the defects through detection of thesignals detected by the photo-detectors through the respectivesynchronization detector circuits 145 a-145 d, it is possible to detectthe defects while keeping the detection sensitivity to be uniform, incomparison with the case of irradiating lights in the form of themulti-spots while changing the wavelengths thereof, and therebyobtaining high-speed.

Also, in a case where no transparent film 800 is formed on the surfaceof the inspection target 2, it is not always necessary to set theinclination angle γ and the detection angle θ to be low in the angle,but they may be set at arbitrary value, within a range from 5 to 90degrees.

Furthermore, in the place of scanning the plural numbers of laser spots,it is also possible to obtain high-speed of inspection, by disposing theplural numbers of detection heads, each of which is unified with thescanning laser illumination system and the detection optic systemtherein, into the direction of aligning the chips 202, in morepreferably, fitting with the pitch of chips.

The technologies shown in FIGS. 12( a)-12(c) and FIG. 13 mentioned aboveare also applicable, for example, into the upper-directed detection ofusing the detection optic system 200 therein.

[Conveyer System 30]

Next, explanation will be made on the conveyer system 30. The stages 31and 32 are for moving the sample-mounting base 34 on the XY plane,thereby having a function of enabling to move the entire surface of theinspection target substrate 1 within the illumination area of theillumination optic system 10. Also, the stage 33 is a Z stage, therebyhaving a function of enabling to move the sample-mounting base 34 intothe direction of an optical axis (i.e., the Z direction) of themagnification-variable detection optic system 20. Further, thesample-mounting base 34 has a function of holding the wafer 1 thereon,as well as, of rotating the inspection target substrate 1 on the plane.And further, the stage controller 35 has a function of controlling thestages 31, 32 and 33, and also the sample-mounting base 34.

[Signal Processing System 40]

Next, explanation will be given about the details of the signalprocessing system 40 for processing outputs from the photo-detectors 26and 640, etc., by referring to FIG. 14. The signal processing system 40comprises; an A/D converter 1301 for converting the signal, which isinputted from each of the photo-detectors 26 and 640, being exchangedtherebetween; a data memory portion 1302 for memorizing detected imagesignal f(i,j) on which A/D conversion is made; a threshold valuecalculation processor portion 1303 for processing calculation of athreshold value upon basis of the detected image signal mentioned above;foreign-matter detection processor portions 1304 a-1304 n, each forconducting a foreign-matter detection process for each of pixel merges,upon basis of the detected image signal 510 obtained from the datamemory portion 1302 mentioned above and the threshold value imagesignals (Th(H), Th(Hm), Th(Lm), Th(L)) obtained from the threshold valuecalculation processor portion 1303; a characteristic-quantity calculatorcircuit 1310 for calculating out characteristic quantities, such as, anamount of scattering lights obtained from defect detection through thelow-angle illumination/the upper-directed detection (i.e., the low-angleillumination by means of the illumination light beams 220 and 230/theupper-directed detection by means of the photo-detector 200), an amountof the scattered lights obtained from defect detection through thehigh-angle illumination (including a middle-angle illumination)/theupper-directed detection (i.e., the high-angle illumination by means ofthe illumination light beams 220, 230 and 240/the upper-directeddetection by means of the detection optic system 200), an amount of thescattered lights obtained from defect detection through the low-angleillumination/the oblique detection (i.e., the low-angle illumination bymeans of illumination light beam 250/the oblique detection by means ofthe side-directed detection optic system 600), and the detected numberpixels indicative of an extent of the defects, etc., for example; anintegrated processor circuit 1309 for classifying the defects, such as,small/large foreign matters or pattern defects or micro-scratches, etc.,on the semiconductor wafer, into each kinds of those defects, upon basisof the characteristic quantity of each of the merges, which can beobtained from the said characteristic-quantity calculator circuit 1310;and a result display portion 1311. The foreign-matter detectionprocessor 1304 a-1304 n are constructed with, each comprising pixelmerge circuit portions 1305 a-1305 n, 1306 a-1306 n, foreign-matterdetection processor circuits 1307 a-1307 n, and inspection areaprocessor portions 1308 a-1308 n, corresponding to each of mergeoperators of, for example, 1×1, 3×3, 5×5, . . . n×n.

In particular, the present invention is characterized by, theforeign-matter detection processor portions 1304 a-1304 n, thecharacteristic-quantity calculator circuit 1310, and the integratedprocessor circuit 1309.

Next, explanation will be made about the operations thereof. First, thesignal obtained from each of the photo-detectors 26 and 640, whileexchanging therebetween, is digitalized within the A/D converter 1301.This detected image signal f(i,j) 510 is stored within the data memoryportion 1302, at the same time, transmitted to the threshold-valuecalculation processor portion 1303. Within the threshold-valuecalculation processor portion 1303, calculation is made upon thethreshold image Th(i,j), and within the foreign-matter detectionprocessor circuits 1307, detection is made upon the foreign matters uponbasis of the signal processed within the pixel merge circuits 1305 and1306, for each of various kinds of merges. Upon the foreign-mattersignal detected and/or the threshold image is treated a processdepending upon the detection point or position, within the inspectionarea processor portion 1308. At the same time, upon basis of the signalsobtained from the pixel merge circuits 1305 a-1305 n and 1306 a-1306 n,the foreign-matter detection processor circuits 1307 a-1307 n, and theinspection area processor portions 1308 a-1308 n of the foreign-matterdetection processor portions 1304 a-1304 n, which are provided for eachof the various merge operators, calculation is made on thecharacteristic quantity (for example, the amount of scattered lightsobtained through the high-angle illumination/the upper-directeddetection, an amount of the scattered lights obtained through thelow-angle illumination/the upper-directed detection, an amount of thescattered lights obtained through the low-angle illumination/the obliquedetection, and the number of detected pixels, etc.), and theforeign-matter signal and the characteristic quantity mentioned aboveare integrated within the integration processor portion 1309, andthereby displaying the inspection result on the result display portion1311.

Hereinafter, the details of the above will be mentioned. Firstly, theA/D converter 1301 is a circuit, having a function of convertinganalogue signals, which are obtained from the photo-detectors 26, 640and so on, into digital signals, but preferably has a conversion bitnumber from 8 bits to 12 bits, for example. This is, because of thefacts that it is difficult to detect a minute light, since the smallerthe bit number, the lower the resolution of the signal processing, buton the other hand, there is caused a demerit of increasing a price ofthe apparatus, since the A/D converter is expensive as the bit numbercomes up to be large. Next, the data memory portion 1302 is a circuitfor memorizing the digital signals therein, on which the A/D conversionis made.

However, the threshold-value calculation processor portion 1303 isdescribed in Japanese Patent Laying-Open No. 2000-105203 (2000). Thus,within the threshold-value calculation processor portion 1303,threshold-value image of the detection threshold values (i.e., Th(H) andTh(L)) and verification threshold values (i.e., Th(Hm) and Th(Lm)) iscalculated out from the following equation (2). Where, a deviation ofinput data can be calculated out by (σ(ΔS)=√{square root over ()}(ΣΔS²/n−ΣΔS/n)), and an averaged value of the input data by(μ(ΔS)=ΣΔS/n)). Further, it is assumed that a coefficient (i.e., themagnification) is “k” for setting up the threshold value correspondingto a number “n” of the input data, and that a coefficient is “m”(assuming that “m” is smaller than 1) for verification.Th(H)=μ+k×σ, or Th(H)=μ−k×σ, orTh(Hm)=m×(μ+k×σ), or Th(Lm)=m×(μ−k×σ)  (2)

Or, the threshold-value image data may be changed for each of the areas,which are set up from the inspection area processor portions 1308 a-1308n. In brief, for lowering the detection sensitivity within a certainarea, it is sufficient to increase the threshold value in that area.

Next, explanation will be give about the pixel merge circuit portions1305 and 1306 for signals, by referring to FIGS. 15 and 16. The mergecircuit portions 1305 a-1305 n and 1306 a-1306 n are constructed withmerge operators 1504, each being different from each other. Each of themerge operators 1504 has a function of combining the detected imagesignal f (i,j), which can be obtained from the data memory portion 1302,and the threshold-value image signal 520, which can be obtained from thethreshold-value calculation processor portion 1303, including theverification threshold-value images Th(H), Th(L), Th(Hm) and Th(Lm)within a region of n×n pixels for each, and it is a circuit foroutputting an averaged value of n×n pixels, for example. Herein, thepixel merge circuit portion 1305 a or 1306 a is made up with the mergeoperator for merging 1×1 pixel, the pixel merge circuit portion 1305 bor 1306 b with the merge operator for merging 3×3 pixels, the pixelmerge circuit portion 1305 c or 1306 c with the merge operator formerging 5×5 pixels, . . . and the pixel merge circuit portion 1305 n or1306 n with the merge operator for merging n×n pixels, for example.Thus, the merge operator for merging 1×1 pixel provides the input signal510 or 520 as it is, to be an output therefrom.

With the threshold image signals, since each one is made up with four(4) image signals (i.e., Th(H), Th(L), Th(Hm) and Th(Lm)), there isnecessity of providing four (4) pieces of the merge operators Op in eachof the pixel merge circuit portions 1305 a-1306 n. Accordingly, fromeach of those pixel-merge circuit portions 1305 a-1306 n are outputtedthe detection image signals, being treated with merge processing in thevarious kinds of merge operators 1504, in the form of merge-processdetection image signals 431 a-431 n. On the other hand, from each ofthose pixel-merge circuit portions 1306 a-1306 n are outputted four (4)threshold image signals (Th(H), Th(Hm), Th(Lm) and Th(L)), being treatedwith the merge process thereon within the various kinds of mergeoperators Op1-Opn, in the form of merge-processed threshold-value imagesignals 441 a(441 a 1-441 a 4)-441 n(441 n 1-441 n 4). However, themerge operator within each of the pixel-merge circuit portions 1306a-1306 n is same to one another.

Herein, explanation will be made about an effect of merging the pixels.With the foreign-matter inspecting apparatus according to the presentinvention, it is needed to detect, not only the fine or microscopicforeign matters, always, but also thin-film like foreign mattersextending or spreading over a region of several μm, without looking overthereof. However, the image signal detected from the thin-film likeforeign matters not always sufficiently large enough; i.e., the S/Nratio is low for a unit of one (1) pixel of the detection image signal,and therefore, resulting into the look over thereof, sometimes.Therefore, if bringing the level of the detection image signal averagedfor one (1) pixel up to S and dispersion of averaging be σ/n, then thelevel of the detection signal comes to be n²×S through conducting theconvolution operation upon the pixels, which are cut out by a unit ofn×n pixels corresponding to the size of the thin-film like foreignmatters, while the dispersion (N) is σ×n. Accordingly, the S/N ratio isn×S/σ. Therefore, through the convolution operation while cutting outthe pixels by a unit of n×n corresponding to the thin-film like foreignmatters, it is possible to increase the S/N ratio up to that by n times.

With the fine or microscopic foreign matters of about one (1) pixel unitin the size, since the detected image signal level is S and thedispersion is σ, which can be detected by the one (1) pixel unit,therefore the S/N ratio is S/σ. If conducting the convolution operationupon the n×n pixels, which are cut out with respect to the fine foreignmatters of about one (1) pixel unit, then the detected image signallevel is S/n² and the dispersion is n×σ; therefore, the S/N ratio isS/n³/σ. Accordingly, with such the fine or microscopic foreign mattersof about one (1) pixel unit in the size, an improvement can be obtainedif applying the signal of the pixel unit as it is.

Although the explanation was made about the example, in which the mergearea or region is a regular square (i.e., n×n pixels), in the presentembodiment; however, the merge area may be an oblong (i.e., n×m pixels).In this instance, detection of the foreign matters having directionalproperty (i.e., the orientation) can be made in the form of the oblong,as well as, the detecting pixels on the photo-detectors 26 and 640;however, it is effective to process the signal processing in the squareform.

Also, though the explanation was made about the embodiment of outputtingthe average value of n×n pixels, in particular, as the function of themerge operator; however, a maximum value, a minimum value or a centralvalue of the n×n pixels may be outputted therefrom. In the case ofapplying the central value, there can be obtained a stable signal.Further, as an output value may be a value, which can be obtainedthrough multiplying or dividing the average value of the n×n pixels by aspecific value.

Next, FIG. 16 is a view for showing an embodiment of the foreign-mattersdetection processor circuit 1307. In this FIG. 16, the details are shownof the pixel merge circuit portion 1305 a and 1306 a, each for mergingthe n×n pixels, and also of the pixel merge circuit portion 1305 n and1306 n, each for merging the n×n pixels.

And, the foreign-matter detection processor circuits 1307 a-1307 n areconstructed with comparators 1601 a-1601 n for comparing the levels ofmerge-process difference signals 471 a-471 n and merge-process thresholdsignals 441 a-441 n, respectively, and detect-position determinationprocessor portions 1602 a-1602 n for identifying detecting points orpositions of the foreign matters. In the comparator circuits 1601 a-1601n are provided delay memories 451 a-451 n for delaying the detectedimage signals, which are obtained from the pixel merge circuits 1305a-1305 n and are treated with the pixel merge thereupon, for repetitionformed, such as, on a chip, for example, and difference processorcircuits 461 a-461 n for forming difference signals between the detectedimage signals 431 a-431 n and reference image signals, which are delayedthrough the delay memories mentioned above and are treated with thepixel merge thereupon. Accordingly, the comparator circuits 1601 a-1601n are those for making comparison with the merge-process threshold valueimage Th(H) (i,j), Th(Hm) (i,j), Th(Lm) (i,j) and Th(L) (i,j), which areobtained from four (4) pieces of the pixel merge circuits Op of each ofthe pixel merge circuit portions 1306 a-1306 n, and have a function ofdetermining the foreign matters, if the merge-process differencedetection signals 471 a-471 n are larger than the merge-processthreshold value image Th(i,j), for example.

In the present embodiment, there are prepared four (4) kinds of thethreshold values, thereby conducting the determination process uponmerge-process threshold value images 1603, 1604, 1605 and 1606, for eachof the merge operators, within the comparator circuits 1601 a-1601 n.

Next, explanation will be made about the detect-position determinationprocessor portions 1602 a-1602 n. The process of detection-positiondetermination is that for identifying the chip, on which the foreignmatters or the defects lies thereon, corresponding to the various kindsof merge operators, thereby calculating out the positional coordinates(i,j). The way of thinking of the present process is to identify thechip, on which the foreign matters or the defects are detected, by usingthe results detected through the detection threshold values (i.e., Th(H) and Th(L)) and the verification threshold values (i.e., Th(Hm) andTh(Lm)), which are the threshold values smaller than the said detectionthreshold values in the value thereof.

Next, explanation will be made about the inspection area processorportions 1308 a-1308 n. The inspection area processor portions 1308a-1308 n are used when deleting data of an area (including an areawithin the chip) where no inspection must be made, or when changing thedetection sensitivity for each of the areas (including an area withinthe chip), or on the contrary when selecting an area to be inspected,with respect to the detected signals of foreign matters and/or defects,which can be obtained from the foreign-matter detection processorcircuits 1307 a-1307 n by identifying the chip. Within those inspectionarea processor portions 1308 a-1308 n, in particular, in a case wherethe detection sensitivity can be lowered down, within the area on theinspection target substrate 1, it is possible to set the threshold valueto be high, for that area, which can be obtained from a threshold valuecalculator portion (not shown in figures) of the threshold-valuecalculation processor portion 1303, or apply a method of remaining onlythe data of foreign matters within the area where the inspection shouldbe made, among the data of foreign matters outputted from theforeign-matter detection processor circuits 1307 a-1307 n, upon basis ofthe coordinates of the foreign matters.

Herein, the area where the detection sensitivity can be lowered downmeans an area having a low density of the circuit patterns on theinspection target substrate 1, for example. An advantage of loweringdown the detection sensitivity lies in that the number of pieces ofdetections can be reduced down, effectively. Thus, with the inspectingapparatus having high sensitivity, sometimes, it detects the foreignmatters of several-tens thousand (10,000) pieces thereof. In such theinstance, what being truly important or serious are the foreign matterslying within the area where the circuit patters are formed, and it isthe nearest way for improving yield or productivity in devicemanufacturing to take countermeasure to deal with such serious foreignmatters. However, in the case where the inspection is made all over thearea or region on the inspection target substrate 1 with the samesensitivity, since the serious foreign matters are mixed up withnon-serious foreign matters, it cannot be made, easily, to extract theserious foreign matters. Then, within the inspection area processorportions 1308 a-1308 n, upon basis of CAD information or threshold mapinformation within the chip, it is possible to extract the seriousforeign matters with high efficiency, by lowering the detectionsensitivity in the areas, which give no ill effect or influence upon theyield rate or productivity. However, as the method of extracting foreignmatters, there may be applied others than that of changing the detectionsensitivity, but it is also possible to extract the serious foreignmatters through classifying the foreign matters, which will be mentionedlater, or to pick up the serious foreign matters upon basis of the sizesthereof.

Next, explanation will be made about the integration processor portion1309 and the inspection result display portion 1311 thereof. Theintegration processor portion 1309 has a function of integrating theforeign-matter detection results, which are processed in parallel withinthe pixel merge circuits 1305 and 1306, or integrating thecharacteristic quantities, which are calculated out within thecharacteristic-quantity calculator circuit 1319, and the detectionresults of foreign matters, and/or transmitting the results to theresult display portion 1311. Preferably, the integration process ofthose inspection results is conducted with an aid of a PC, etc., formaking the process contents being easily changeable.

First of all, explanation will be made on the characteristic-quantitycalculator circuit 1310. This characteristic quantity means a value,indicative of the feature or characteristics of the detected foreignmatters and/or defects, and the characteristic-quantity calculatorcircuit 1310 is a processor circuit for calculating out thecharacteristic quantity mentioned above. As the characteristic quantity,there can be listed up, for example, an amount of lights reflectedand/or diffracted upon the foreign matters and/or defects (i.e., anamount of scattered lights) (Dh and D1), which are obtained through thehigh-angle illumination/the upper-directed detection, the low-angleillumination/the upper-directed detection, and the low-angleillumination/the oblique detection, the number of detecting pixels, theconfiguration of the foreign-matter detecting area and the direction ofan inertia main axis thereof, the detecting position of foreign matterson the wafer, the kinds of circuit patterns on the background, and thethreshold values when detecting the foreign matters, etc.

Next, explanation will be made about an embodiment of DFC within theintegration processor portion 1309.

Thus, since being inputted with the foreign-matter detection signals,upon which various kinds of pixel merges are treated, then theintegration processor portion 1309 is able to classify the foreignmatters into “large foreign matters”, “fine foreign matters”, “foreignmatters having a low height”, as shown in FIG. 17. This FIG. 17 is atable for showing the relationships between the classifying criteria andclassified results. This FIG. 17 shows an example of applying thedetection result between the result, which is detected through the 1×1pixel and treated with the merge process thereupon, and the result,which is detected through the 5×5 pixels and treated with the mergeprocess thereupon. Thus, from the foreign-matter detection processorcircuits 1307 a and 1307 c can be obtained the inspection results uponthe 1×1 pixel and the 5×5 pixels through the signal processor circuit.With using those, the classification is conducted according to FIG. 17.Thus, a certain foreign matter can be detected upon both the 1×1 pixeland the 5×5 pixels, and it is classified to be “large foreign matters”.Also, if it can be detected upon the 1×1 pixel but not upon the 5×5pixels, then it is classified to be “fine foreign matters”, and furtherif it cannot be detected upon the 1×1 pixel but upon the 5×5 pixels,then it is classified to be “foreign matters having a low height”.

FIG. 18 shows an embodiment of the display of inspection results,including therein the classifying results mentioned above. The displayof the inspection results mentioned above is made up with positioninformation 2501 of the foreign matters obtained from thedetect-position determination processor portions 1602 a and 1602 c,category information 2502 of the classifying results obtained from theintegration processor portion 1309, and numbers of foreign matters foreach of the categories. With the present embodiment, the position offoreign matters is displayed through the position information of thesaid foreign matters, at the same time displaying the classificationcategories thereof with an aid of display marks, together. Also, thecontents for each of the marks of classification categories are shownwithin the classification category information 2502. Further, the numberof foreign matters 2503 for each category indicates the number of piecesof the foreign matters, which are classified into each of thecategories. Changing the display for each of the categories in thismanner, there can be obtain an advantage of seeing the distribution ofeach the foreign matters at a glance.

Next, explanation will be made about an embodiment of a method, formeasuring the sizes of foreign matters, according to the presentinvention. The present method is one of utilizing the fact that there isa proportional relationship between the sizes of foreign matters and thelight amount detected upon the photo-detector 26. Namely, in particular,if the foreign matters are small, there is the relationship that thelight amount D detected is in proportional to 6^(th) power of the size Gof the foreign matters, in accordance with the theory of scattering ofMie. Accordingly, the characteristic-quantity calculator circuit 1310 isable to measure the size of foreign matters from an equation (3), whichwill be shown below, upon basis of an amount D of the detected lights,the size G of foreign matters, and a proportional coefficient ε, andthereby it provides it to the integration processor portion 1309.G=ε×D ^((1/6))  (3)Where, the proportional coefficient ε may be obtained from the lightamount detected from the foreign matters, which size is already known,in advance, thereby to be inputted thereto.

Next, explanation will be made on an embodiment of the method forcalculating out the detected light amount D, by referring to FIGS. 19(a) and 19(b). FIG. 19( a) shows an image of the fine foreign matterportion, which is produced upon basis of digital image signal of thefine foreign matters (i.e., the image signal obtained through A/Dconversion upon the signal of the photo-detector 26), which can beobtained from the data memory portion 1302, in relation to the fineforeign matters detected within the foreign-matter detection processorcircuit 1307. The fine foreign matter portion 2601 indicates the signalof the fine foreign matters. FIG. 19( b) shows A/D conversion values(i.e., gradation values of the pixels, for each) of the fine foreignmatters 2601 shown in FIG. 19( a) and an image in vicinity thereof. Thisexample shows an example when conducting the A/D conversion of 8 bits,wherein the foreign-matter signal portion 2602 indicates the detectedsignal from the fine foreign matters. Herein, “255” at a center of theforeign-matter signal portion 2602 indicates that an analog signal is insaturation, and portions of “0” other than the foreign-matter signalportion 2602 indicate that they are signals obtained from others thanthe fine foreign matters. As a method for calculating out an amount D ofdetected lights from the fine foreign matters, the sum is calculated outof the respective pixel values of the foreign-matter signal portion 2602shown in FIG. 19( b). For example, in the example of FIG. 19( b), thedetected light amount D of the fine foreign matters 2601 is “805”, i.e.,the sum of the values of the respective pixels.

Next, explanation will be made about another embodiment of method forcalculating out the detected light amount D. The way of thinking in thepresent embodiment lies in that, the saturated portion of the foreignmatter signal portion 2602 shown in FIG. 19( b) is compensated with anaid of approximation of the Gauss distribution; thereby, obtaining animprovement of accuracy of calculation of the detected light amount.About this compensation will be made explanation, by referring to FIG.20. This FIG. 20 is a view for presenting the Gauss distribution in thethree dimensional (3D) manner. This FIG. 20 shows the case where thesignal is saturated at y=y₀, and a method that will be explainedhereinafter, about calculating out the detected light amount of theentire Gauss distribution, in the portion below y=y₀ shown in FIG. 20;i.e., in the case where the detection light amount can be obtained in aportion of V₃. First of all, it is assumed that a volume of the entireGauss distribution shown in FIG. 20 is V₁, that of portion above y=y₀V₂, and that of portion below y=y₀ V₃, respectively. It is also assumedthat the cross-section configuration can be obtained from the followingequation (4) on the x-axis of the Gauss distribution shown in FIG. 20:y=exp(−x ²/2/σ²)  (4)

In this instance, V₁ can be expressed by the following equation (5)through conducting integration around the y-axis:V ₁=2×π×σ²  (5)

Further, V₂ can be expressed by the following equation (6):V ₂=2×π×σ²(y ₀×log(y ₀)+1−y ₀)  (6)Where, “log” in the above equation is indicative of calculation of thenatural logarithm.

Herein, rewriting a volume ratio V₁/V₃ to be CC, since CC can becalculated by the following equation (7), the following equation (8) canbe calculated from the equations (5) and (6) mentioned above:CC=V ₁/(V ₁ −V ₂)  (7)CC=1/(y ₀×(1−log(y ₀)))  (8)

Herein, assuming that signal width of the saturated portion is SW, sinceit can be expressed by the following equation (9), then CC can beexpressed by the following equation (10):y ₀=exp(−SW ²/2/σ²)  (9)CC=exp(SW ²/2/σ²)/(1+SW ²/2/σ²)  (10)

Accordingly, if the detected light amount is V₃, which is obtained as isshown in FIG. 19( b), the volume V₁ of the entire Gauss distribution canbe calculated by the following equation (11), and therefore it is enoughto put this V₁ into the detected light amount after compensation.However, it is necessary to calculate out the signal width SW:V ₁ =V ₃×exp(SW ²/2/σ²)/(1+SW ²/2/σ²)  (11)

As was mentioned above, the explanation was made about the method forcalculating the detected light amount D, however in the case of a viewfield of the magnification-variable detection optic system 20 is wide,there might be a case where an error is caused due to distortion of thelens within the view field. In this case, compensation may be madecorresponding to the lens distortion thereof.

In the present embodiment, although using the value of the sum ofsignals of the foreign-matter signal portion 2602 as the detected lightamount, however it should not always the sum of signals, but it may bethe maximum value of the foreign-matter signal portion 2602. As anadvantage of the case of using the maximum value, it is possible to makethe scale of electric circuitry small, and in the case of using the sumof signals, it is possible to reduce sampling errors on the signals,thereby obtaining a stable result.

Furthermore, with the display screen, it may be displayed on a displaymeans 52, which is provided within the total controller portion 50.

Next, explanation will be given about other embodiment of classificationof foreign matters or defects, which is conducted within the integrationprocessor portion 1309, by referring to FIG. 21 and FIGS. 22( a) and22(b). FIG. 21 shows a sequence of classifying the foreign matters uponbasis of the results, which are obtained through conduction ofinspection by two (2) times made within the integration processorportion 1309.

Firstly, inspection is made upon the wafer 1 under a first inspectioncondition (S221). In the first inspection, the coordinate data of theforeign matters, which can be obtained from the foreign-matter detectionprocessor circuit 1307, and the characteristic quantities of therespective foreign matters, which can be obtained from thecharacteristic-quantity calculator circuit 1310, are reserved within amemory device (not shown in the figure) (S222). Next, inspection is madeupon the wafer 1, but under a second inspection condition different fromthe first inspection condition (S223), and in this second inspection,the coordinate data of the foreign matters obtained from theforeign-matter detection processor circuit 1307, and the characteristicquantities of the respective foreign matters obtained from thecharacteristic-quantity calculator circuit 1310, are also reservedwithin the memory device (not shown in the figure) (S224). In thisinstance, for example, if irradiating the illumination lights from anangle near to the wafer surface under the first inspection condition,for example, then as the second inspection condition, it is preferableto select a condition of irradiating the illumination lights from anangle near to a normal line on the wafer surface (i.e., a high-angleillumination condition). Also, when making an inspection upon the wafer1 under the second inspection condition, the characteristic quantity atthe coordinates where the foreign matters are detected under the firstinspection condition is memorized, irrespective of detecting or not offoreign matters under the second inspection condition.

Next, comparison is made between the coordinate data obtained as theresult of the first inspection and the coordinate data obtained as theresult of the second inspection (S225), and then classification is madefrom the respective characteristic quantities thereof, while assumingthat the foreign matters near to each other in the coordinates thereofbe the same thing (S226). Herein, as one embodiment of the method fordetermining vicinity of the coordinate data, if assuming that thecoordinate data obtained from the first inspection result are “x₁” and“y₁”, that the coordinate data obtained from the second inspectionresult are “x₂” and “y₂”, and that a comparison radiator is “r”, thendetermination may be made that the data fitting to the followingequation (12) to be the same thing:(x ₁ −x ₂)²+(y ₁ −y ₂)² <r ²  (12)

Herein, “r” may be set to be zero (0) or a value by taking the erroraccompanying the apparatus into the consideration. As the measuringmethod, for example, calculation may be made upon the value of left-handside of the equation (12) with the coordinate data of the foreignmatters at several points, and then from the averaged value thereof anda standard deviation value, the value calculated out from the equation(13) may be set to “r”, for example.r ²=average value+3×standard deviation  (13)

Further, explanation will be made about the method for classifying theforeign matters from the foreign-matter information considered to be thesame thing, by referring to FIGS. 22( a) and 22(b). In FIG. 22( a), ontothe horizontal axis thereof is set the scattered light amount (D1)obtained by the first inspection mentioned above (i.e., the low-angleillumination), while onto the vertical axis the characteristic quantity,i.e., the scattered light amount (Dh) obtained by the second inspection(i.e., the high-angle illumination). In FIG. 22( b), onto the horizontalaxis thereof is set the scattered light amount (D1′) obtained from theside-directed detection optic system 600 under the low-angleillumination, while onto the vertical axis is set the scattered lightamount (Dh′) obtained therefrom under the high-angle illumination. Inthose FIGS. 22( a) and 22(b), a reference numeral 3501 depicts points,being plotted corresponding to each of the characteristic quantities ofthe foreign matters, which are considered to be the same thing. In thepresent embodiment, one (1) point indicates one (1) piece of foreignmatter. Also, a reference numeral 3502 depicts a classification curvefor classifying the foreign matters detected during the inspection.Those FIGS. 22( a) and 22(b) show a case of dividing into two (2) areasby the classification line, i.e., an area 3503 and an area 3504. As amethod for classifying, if the above-mentioned foreign matters detectedshould be plotted within the area 3503 in FIG. 22( a), they areclassified to be “large foreign matters or scratches”, while they areclassified to be “small foreign matters” if they should be plottedwithin the area 3504. Also, detected things 4510 are classified to bethe defects within film, lying inside the transparent film 800, if thescattered light amount (D1′) within the side-directed detection opticsystem 600 is smaller, comparing to the scattered light amount (D1)under the low-angle illumination and the scattered light amount (Dh)under the high-angle illumination, as is shown in FIG. 22( a). By theway, in the case of an upper-directed detection under the low-angleillumination, the brightness comes down due to spreading of theillumination light beam upon the wafer, thereby lowering thesensitivity; therefore, the detection sensitivity of the upper-directeddetection is lower than that of the side-directed detection.

Herein, it is necessary to determine the classification line 3502, inadvance. As a method for determining it in advance, plotting thedetected things in several numbers thereof on a graph of FIGS. 22( a)and 22(b), which are already known to be the large foreign matters orthe small foreign matters in advance, the classification line 3502 isset up, so that the detected things can be divided, correctly. Or,calculating out the characteristic quantity obtainable from the foreignmatters, through simulation thereon, the classification line 3502 may beset up from the result thereof. Herein, as a method of affirming thekinds of foreign matters, for example, the classification may be madewith using the detected things upon the wafer, which are already knownabout the defects coordinate and the kinds thereof through a reviewapparatus, such as, an observatory optic microscope 60 or a SEM, etc.,which is mounted within the inspecting apparatus. With the reviewapparatus, including the observatory optic microscope 60 mounted withinthe inspecting apparatus, it is possible to make the classificationwithin a short time, while in the case of using the SEM, it is possibleto make the classification with high resolution. The detected things arethe foreign matters, the scratches, or the foreign matters withintransparent film, etc., in the kind thereof. Upon setup of theclassification line 3501, the threshold value may be set at such acertain value of the scattered light amount obtainable under thelow-angle illumination, that there occurs no error of detecting electricnoises within the detector 26 to be the foreign matters. Also, firstlycalculation is made upon a position of the center of gravity, for eachof the groups of large foreign matters and small foreign matters,thereby obtaining the standard deviation at each of the plotted pointstherefrom. Next, an orthogonal bisector is drawn, as the classificationline 3502, at a point on a straight line, satisfying Lx(r1/r1+r2)),where distance is “L” of a line joining between the respective positionsof the center of gravity, and radii of the standard deviation from therespective positions of the center of gravity are “r1” and “r2”,respectively.

In the present embodiment, though the explanation was given about theexample of conducting the inspection two (2) times; however, in a casewhere an improvement can be obtained upon the classifying performanceswhen increasing up the kinds of the characteristic quantities (forexample, the detecting pixel number: corresponding to an area Q of thedefect), the characteristic quantities (i.e., detecting pixel number)may be obtained of the foreign matters, by conducting the inspectionthree (3) times thereupon.

Next, explanation will be given about further other embodiment of theclassification of foreign matters or defects, which will be executedwithin the inspection result integration processor portion 1309, byreferring to FIG. 23. This FIG. 23 shows a sequence of an embodiment formaking the classification with using the characteristic quantities,being calculated upon three (3) kinds of optical conditions afterconducting the inspection only one (1) time.

First, inspection is made upon the wafer under the first opticalcondition (S241), and reservation is made on both the coordinate data offoreign matters, obtained from the foreign-matter detection processorcircuit 1307, and the characteristic quantities for each of the defects,obtained from the characteristic-quantity calculator circuit 1310(S242). Next, the optical condition is changed in the foreign-matterinspecting apparatus according to the present invention. This includes,for example, the irradiation angle and/or the illumination direction ofthe illumination optic system, and/or the detecting direction (i.e., theupper-directed or the oblique) by means of the detection optic system.Also, the magnification (or, magnifying power) of the detection opticsystem may be changed, or the optical filters may be exchanged. It isassumed that the second optical condition is that, upon which suchchanges as mentioned above can be made.

After changing the optical condition into the second optical condition,the wafer 1 is moved on the conveyer system 30, to the position on thecoordinate of the foreign matters, which are reserved, as was mentionedabove, then upon basis of the detected image signal, which can bedetected upon the photo-detector 26 and obtained through A/D conversionthereof under the second optical condition, the characteristicquantities of foreign matters are calculated out within thecharacteristic-quantity calculator circuit 1310 (S243). Further,calculation will be made in the similar manner, when calculating out thecharacteristic quantities under the third optical condition (S244). Inthis instance, it is preferable that the first optical condition, thesecond optical condition and the third optical condition differ from oneanother, respectively.

The way of thinking of this classifying method will be explained byreferring to FIG. 24. This FIG. 24 shows a characteristic quantityspace, in which the three (3) kinds of characteristic quantities are setup to the three (3) axes thereof. As those three (3) axes, for example,a characteristic quantity 1 is the characteristic quantity (for example,the scattered light amount (Dh)) obtained from defects under the firstoptical condition (for example, the high-angle illumination), the secondcharacteristic quantity 2 is the characteristic quantity (for example,the scattered light amount (D1)) obtained from defects under the secondoptical condition (for example, the low-angle illumination), and a thirdcharacteristic quantity is the characteristic quantity (for example, thedetecting pixel number: a flat area of the defects) obtained fromdefects under the third optical condition (for example, the high-angleillumination of being the first optical condition and the low-angleillumination of being the second optical condition). In such thecharacteristic space, (number of classification categories—1) pieces ofclassification boundaries are set up. Since this FIG. 24 shows anexample of conducting the classification into three (3) kinds from three(3) kinds of characteristic quantities, therefore it is sufficient toset up the classification boundaries in the number of two (2) or morethan that.

In particular, as those three (3) kinds of characteristic quantities, ifsetting up the scattered light amount (i.e., the detection light amount)(Dh) from defects under the high-angle illumination, the scattered lightamount (i.e., the detected light amount) (D1) from defects under thelow-angle illumination, and the detecting pixel numbers of defects underthe high-angle illumination and the low-angle illumination, it ispossible to classify the defects, at least, into three (3) kinds ofcategories (the foreign-matter defects, the scratch defects, and thecircuit-pattern defects, for example). Further, since the detectingpixel number of defects (i.e., the flat area of defects) are taken ormemorized as one of the characteristic quantities, therefore, it is alsopossible to classify the category of the foreign-matter defects into thelarge foreign matters and the small foreign matters, as shown in FIG.22.

Also, as those three (3) characteristic quantities, if setting up thescattered light amount from defects at high image-forming magnification,the scattered light amount from defects at low image-formingmagnification, and the detecting pixel number of defects, it is possibleto make classification, at least into the large foreign-matter defectsand the small foreign-matter defects, easily. Also, from thecharacteristic quantity of the defect image, which can be obtained fromthe photo-detector 640, it is possible to classify the defects, such as,the fine foreign matters and/or the scratches (i.e., scratchingdefects), etc., on the transparent film.

Then, FIG. 24 shows the example of setting up the classificationboundaries 4501 and 4502. As a method for classification, firstly thethree (3) characteristic quantities mentioned above are plotted withinthe characteristic quantity space shown in FIG. 24 (S245 sown in FIG.23). Then, the foreign matters belonging to the area or region dividedby the classification boundaries 4501 and 4502 are classified into thecategory “a” (for example, the foreign-matter defects), the category “b”(for example, the scratch defects), and the category “c” (for example,the circuit-pattern defects), for example (S246 shown in FIG. 23). ThisFIG. 24 shows the example of classifying about thirty (30) pieces ofdefects into the category “a”, the category “b” and the category “c”,while changing the display marks thereof, for each of the defectsclassified into the respective categories. Thus, those classified intothe category “a” (for example, the foreign-matter defects) is displayedby “◯”, those classified into the category “b” (for example, the scratchdefects) by “▴”, and those classified into the category “c” (forexample, the circuit-pattern defects) by “x”, respectively.

Next, explanation will be given about a method for setting up theclassification boundaries, by referring to FIGS. 25( a) through 25(c).Those FIGS. 25( a) through 25(c) show two-dimensional (2D) space ofcharacteristic quantities, in each of which one of the three (3) kindsof the characteristic quantities is set onto one (1) axis thereof,respectively. The characteristic quantity space 4601 makes up a graphfor making classification from a relationship between the characteristicquantity 1 and the characteristic quantity 2, and the characteristicquantity spaces 4602 and 4603 make up graphs for making classificationfrom relationships between the characteristic quantity 1 and thecharacteristic quantity 3, and between the characteristic quantity 2 andthe characteristic quantity 3, respectively.

As a method for setting up the classification boundaries, firstly intothe characteristic quantity spaces 4601, 4602 and 4603 are plotted thecharacteristic quantities of the foreign matters, the classificationcategories of which are already known. Herein, when making plots intothe characteristic quantity spaces, the difference in the category isalso presented, by changing the display mark or the like, for each ofthe categories thereof. For example, FIGS. 25( a) through 25(c) showexamples, each displays the category “a” by “0”, the category “b” by“A”, and the category “c” by “x”, respectively.

Next, within those characteristic quantity spaces 4601, 4602 and 4603,the classification boundaries 4604, 4605 and 4606 are established at theposition, so as to enable to divide the categories, for each. Herein, ifthe categories overlap in plural number thereof, there is no necessityof establishing the classification boundary between them. For example,since the category “a” is distributed at the position separated fromother categories “b” and “a” within the characteristic quantity space4601, then the classification boundary 4604 should be established forclassifying the category “a” separated from the categories “b” and “a”;however, since the categories “b” and “c” overlap with each other in thedistribution thereof, there is not always necessity of establishing theclassification boundary between them. When conducting the classificationupon the foreign matters, they are classified into the category “a” orthe others, by using this characteristic quantity space 4601. In thesimilar manner, within the characteristic quantity spaces 4602 and 4603are established the classification boundaries 4605 and 4606,respectively, thereby to be used when conducting the classification uponthe foreign matters.

The explanation was made about the method for establishing theclassification boundaries, in the above. In the present example, theexplanation was given on the case of dividing the area or region intotwo (2) spaces by means of the classification boundary; however, whenthe categories are divided into three (3) or more in the distributionthereof, there may be established a plural number of classificationboundaries for dividing the area or region into plural numbers thereof.Also, the classification boundary may be established with an aid of astraight line, or a curved line. Or, a user may set up theclassification area or region, manually, or setting may be made throughautomatic calculation thereof. In the case of making setup manually,there is an advantage that the user can determine it/them arbitrarily,while in the case of making setup automatically, errors can be loweredthrough setting up made by a man. Herein, as a method for making setupautomatically, for example, the center of gravity in the distribution iscalculated out for each of the categories within one (1) piece of thecharacteristic quantity space, and an orthogonal bisector of a straightline connecting between the centers of gravity may be adapted to be theclassification boundary. It is also possible to display a separation orisolation rate or ratio of each category together, within a spacedefined between the respective characteristic quantities.

An example of displaying the separation rate thereon is shown in FIG.26. In this FIG. 26, a reference numeral 4701 indicates the display ofthe separation rate. Herein, as such the separation rate, there may bemade a display on which degree the foreign matters of the same categoryare included within the area or region, which is separated by aseparation boundary, for example. As an advantage of displaying theseparation rate, it is possible for the user to grasp the separationperformance of the apparatus, easily.

However, in the present embodiment, there was explained about the caseof applying the characteristic quantities calculated out under the three(3) kinds of optical conditions; however, there is no necessity ofrestricting to the three (3) kinds thereof, always; but it may beapplied into a case where the characteristic quantities are calculatedout under plural kinds of optical conditions or a case where the pluralnumbers of characteristic quantities can be obtained under one (1) kindof the optical condition.

Next, explanation will be given about other embodiment; in particular,relating to display of the inspection result obtained from the signalprocessing system 40, to be displayed on the display means 52, forexample, by the total controller portion 50.

A display shown in FIG. 27 comprises position information 3801 of theforeign matters or defects detected, a detection number 3802 of theforeign matters or defects, and a histogram 3803 of sizes of the foreignmatters or defects detected. However, the present embodiment shows thecase where scratches are detected, as to be the defects.

In more details thereof, the position information 3801 indicates theposition of the foreign matters or scratches on the wafer. However, thepresent embodiment shows a case where the foreign matters are indicatedby “◯”, while the scratches by “▴”. Also, the detection number 3802 isthe number of pieces of the foreign matters or the scratches detected.Further, the graphs 3803 are histograms between the detection number andthe sizes of the foreign matters or the scratches detected. Displayingthe things detected by the defects inspecting apparatus according to thepresent invention, in this manner, enables the distribution of theforeign matters or the scratches to be seen at glance.

A display shown in FIG. 28 comprises, an inspection map 3901 for showingthe detecting positions of the detected things (i.e., of the foreignmatters or the scratches), a histogram 3092 of sizes of the detectedthings, and a review image 3903 of the foreign matters. In the presentembodiment, there is shown an example, where the total number or a partof the things detected are displayed, in relation to the inspection map3901 and the histogram 3902. Also, in relation to the review image 3903,it is an example of displaying a view image of the things, which isdetected by sampling them for each size thereof; i.e., there is shown acase of displaying six (6) pieces of the review images of foreignmatters, each being equal or greater than 0.1 μm and less than 1 μm, aswell as, six (6) pieces of the review images of foreign matters, eachbeing equal or greater than 1 μm, in the present embodiment.

Herein, the review image 3903 may be an image, which can be obtainedthrough the lights reflected and/or diffracted from the foreign mattersdetected by the detectors 26 and 640, or may be an image by means of anoptical microscope 60 of using a white light source therein or a reviewapparatus of using a white light source therein, which will be mentionedlater. In case of displaying the image obtained through the laserlights, it can be displayed just after completing the inspection, if theimage is remained within the memory devices 53, 1302, etc., during theinspection of those detected things; therefore, there can be obtained aadvantage of enabling confirmation upon the detected things, quickly.Also, in the case where the image is displayed, which is obtainedthrough the optical microscope 60, it is enough to take an observatoryimage after completing the inspection, and there can be obtain an image,being clearer than the image obtained through the laser lights. Inparticular, when observing the foreign matters or detects less than 1μm, and therefore it is preferable to adopt a microscope having highresolution, applying the ultra violet (UV) rays into the light sourcethereof.

And, it is also possible to display the position of the detected things,which are displayed on the review image 3903 mentioned above, on theinspection map 3901 together therewith. Although the explanation wasmade on the case where the preview images to be displayed are six (6)pieces for each, in the present embodiment; however, there is nonecessity of limiting to six (6) pieces, and therefore, the foreignmatters or defects may be displayed in the total number thereof, or onlyof a certain rate of the number of pieces with respect to the detectionnumber.

FIG. 29 shows an example of displaying the detected things, beingclassified into the foreign matters and the scratches, as well as, arate or ratio of correctness of classification. This display shown inFIG. 29 comprises, detection numbers 4001 for each of the categoriesclassified, an inspection map 4002 for showing the detecting portion ofthe detected things, and a confirmation screen 4003 of the detectedthings. The confirmation screen 4003 of the detected things, further,comprises a confirmation screen portion 4004 of the detected things,which are classified into the foreign matters by means of the defectsinspecting apparatus according to the present invention, a confirmationscreen portion 4005 of the detected things, which are classified intothe scratches, and a classifying correctness rate display portion 4006.Those confirmation screen portions 4004 and 4005, further, comprise anobservatory screen 4007 of the detected things and also aclassifying-correctness determining portion 4008.

The present embodiment shows an example of classifying the thingsdetected into two (2) categories, wherein a mark “1” indicates theforeign matters and a mark “2” the scratches, on the inspection map4002.

Next, explanation will be made about a method for calculating out theclassifying-correctness rate. First, after making the inspection bymeans of the defects inspecting apparatus according to the presentinvention, observatory images 4007 are displayed, respectively, withinthe confirmation image portions 4004 and 4005. In this instance, thethings detected are displayed on either one of those confirmation imageportions 4004 and 4005, depending upon the result of classification madewithin the defects inspecting apparatus according to the presentinvention. Next, a user of the defects inspecting apparatus, accordingto the present invention, inputs the categories decided by the user intothe classifying-correctness determining portions 4008, which are annexedto the observatory screens 4007, respectively. In the present example,there is shown a case where checking can be made in a checkbox of thecategory that the user selects, as an inputting method thereof, andwithin the confirmation image portions 4004 of the foreign matters, ⅚thereof is checked to be the foreign matters (i.e., the category “1”)and the remaining ⅙ is checked to be the scratches (i.e., the category“2”), as an example. Also, within the confirmation image portions 4005of the scratches, all of them are determined to be the scratches (i.e.,the category “2”), in this example.

After completing the checking mentioned above, the correctness rate orratio is displayed in the classifying-correctness rate display portion4006. As this value is displayed a ratio of coincidence, which can beestablished between the classification result, which can be obtainedfrom the defects inspecting apparatus according to the presentinvention, and the classification result made by the user, for example.Thereafter, in particular, with the detected things, upon which nocoincidence can be made up between the classification result obtainedfrom the defect inspecting apparatus according to the present inventionand the classification result made by the user, the classifyingcondition of those may be renewed, by using the characteristicquantities of the said detected things, for improving an accuracy inclassification.

[Total Controller Portion 50]

Next, explanation will be made about setups and so on for the inspectioncondition (i.e., the inspection recipe), which is executed in the totalcontroller portion 50, etc., by referring to FIGS. 30 through 32. ThisFIG. 30 is a view of showing a flowchart for setting up the inspectioncondition (i.e., the inspection recipe). First, setup of the inspectioncondition (i.e., the inspection recipe), to be conducted within thetotal controller portion 50 before execution of inspection, comprises:setup of a chip layout (S211), rotation fitting on the inspection target(S212), setup of the inspection area (S213), setup of the opticalcondition (S214), setup of the optical filter (S215), setup of detectedlight amount (S216), and setup of the signal processing condition(S217). Further, S218 is an actual execution of an inspection.

Next, explanation will be made about each of those setups, which areexecuted by the total controller portion 50. First, in the setup of achip layout (S211), chip sizes and/or presence or non-presence of chipson the wafer are set into the signal processing system 40, with usingCAD information or the like, within the total controller portion 50.This chip size is necessary to be set up, since it means the distancefor conducting comparison process thereupon. Next, the rotation fitting(S212) is the setup for bringing the aligning direction of chips on thewafer 1 mounted on the stage and the pixel direction of thephoto-detector 26 in parallel with each other, i.e., rotating the wafer1 so as to adjust the rotation shift to be almost “0”. Since conductionof this rotation fitting brings the repetitive patterns on the wafer tobe aligned on one (1) axis direction, the chip-comparison signal processcan be conducted, with easiness. Next, in the setup of inspection areaor region (S213), setting is made on the position where the inspectionshould be made on the wafer, and on the detection sensitivity withinthat inspection area, for the total controller portion 50 to controlsthe signal processing system 40. Conducting this inspection area setup(S213) enables the inspection at the optimal sensitivity upon each ofthe areas on the wafer. The setting method thereof is as was mentioned,by referring to FIG. 15 in the above.

Next, the inspection condition setup (S214) means selection on thedirection and the angle of illumination lights irradiated upon thewafer, and/or selection on the magnifying power of themagnification-variable detection optic system 20, for the totalcontroller 50 to make control upon the illumination optic system 10 andthe magnification-variable detection optic system 20. As a selectingmethod, for example, the setup can be achieved by using an opticalcondition setup window as shown in FIG. 31, for example.

The said optical condition setup screen comprises an illuminationdirection condition 3001 for the illumination system, an illuminationangle condition 3002 for the illumination system, and a detection opticsystem condition 3003 (including the detection direction, such as, theupper-directed one or the oblique one, for example). In this FIG. 31 isshown an example, on which the selection can be made among three (3)kinds on the illumination direction condition 3001, three (3) kinds onthe illumination angle condition 3002, and between two (2) kinds on thedetection optic system condition 3003. A user of the present defectsinspecting apparatus can make selection of the optimal condition whilewatching the contents of the conditions 3001, 3002 and 3003,appropriately. For example, when she/he wishes to make an inspection onthe foreign matters on the surface thereof at high sensitivity, if theinspection target 1 is a wafer during a metal-film deposition process,then it is enough to select “deposition process” from conditions withinthe illumination direction condition 3001, further select “surfaceforeign matters” from conditions within the illumination angle condition3002, and select “upper-directed detection (magnification-variable):high sensitivity inspection” from conditions within detection opticsystem condition 3003; and an example of conducting those selections isshown in FIG. 31. Also, when she/he wishes to make an inspection uponthe defects, such as, the foreign matters and/or the scratches, if theinspection target is the oxidation film, for example, then it is enoughto select “CMP post-process” from conditions within the illuminationdirection condition 3001, and further select “surface foreign matters”from conditions within the illumination angle condition 3002, and select“oblique detection: high speed inspection” from conditions withindetection optic system condition 3003.

Next, the optical filter setup (S215) is for setting up the space filter22 shown in FIG. 1 and/or the optical filter 24 b, such as, of apolarizing element or the like, for the total controller portion 50 tomake control upon the detection optic system 200, etc. This space filter22 is one for shielding the lights reflected and/or diffracted from therepetitive patterns manufacture on the wafer; therefore, it ispreferable to be set up for the wafer having the repetitive patterns,but no necessity to be set up for the wafer having no such repetitivepattern thereon. Also, the polarizing element 24 b is effective if it isused in the situation where edges of wiring patters are etched invicinity of a right angle, for example.

Next, the detection light amount setup (S216) is a sep for adjusting thelight amount to be incident upon the photo-detector 26, for the totalcontroller portion 50 to make control upon the illumination optic system10 or the magnification-variable detection optic system 20. The lightsreflected and scattered from the circuit patterns manufactured on thewafer changes the components to be diffracted thereupon, depending uponthe configuration of the circuit pattern. In more details, in a casewhen the wafer surface is flat, the scattered lights are hardlygenerated thereupon; i.e., almost of those comes to be the regularreflection lights. On the contrary to this, if concave and convex arelarge on the wafer surface, then the scattered lights are generatedthereon much. Accordingly, the lights reflected and/or diffracted fromthe circuit patterns change depending upon the condition of the wafersurface, i.e., the manufacturing process of devices. However, due topresence of the dynamic range on the photo-detector 26, therefore it ispreferable to adjust the light amount to be incident upon in conformitywith that dynamic range. For example, it is preferable so that theamount of lights reflected and/or diffracted from the circuit patternson the wafer comes down to be about 1/10 of the dynamic range of thephoto-detector 26. Herein, as a method for adjusting the light amountincident upon the photo-detector 26, it may be achieved throughadjustment of an amount of the output lights from the laser-light source11, or it may be adjusted with using the ND filter 24 a.

Next, the signal processing condition setup (S217) is for making setupfor detection condition of the defects, such as, foreign matters, etc.,for the total controller portion 50 to make control upon the signalprocessing system 40.

After completing the setups mentioned above, the user can conduct theinspection under the desired condition by conducting the inspectionprocess (S218).

However, as a method for setting up the details, which are explained inthe present embodiment, for example, the details may be inputted fromdesign information of the inspection target by hands, or may be inputtedwith using an input assist function equipped with the foreign-matterinspecting apparatus according to the present invention, or informationmay be obtained from an upper system through a network.

Further, among those setups mentioned above, in particular, theinspection area or region (S213), the inspection condition setup (S214),the optical filter setup (S215), the detection light amount setup (S216)and signal processing condition setup (S217) are not necessarily changeddepending upon the inspection target, always, but they may be a certainvalue irrespective of the inspection target. If setting those at acertain value, it is possible to shorten the time for setting theinspection conditions; however, for obtaining the high sensitivity, itis desirable to make a tuning upon each of the inspection conditions.Also, there is no necessity of conducting it on the inspection area orregion (S213) before the inspection condition setup (S214), always; butit may be set up before the inspection process (S218).

An example of a screen is shown in FIG. 32, for use of setting up thecontents, which are explained in the above. This screen shown in FIG. 32comprises a condition setup sequence 4301, detailed conditions 4302 forcontents of the each setup, a setup-contents display change button 4303,and a help button 4304.

Next, the details thereof will be given. First, the condition setupsequence 4301 shows a flow of the setups of inspection conditions withinthe foreign-matter inspecting apparatus according to the presentinvention. A user may set up the conditions in series from the “chiplayout setup” within the condition setup sequence 4301.

The characteristic of the condition setup sequence 4301 lies in thatindication by arrows 4305 of condition settings enables the user to makethe settings through the shortest sequence, but without an error. Also,as other characteristics thereof, items are separated into thosenecessary to be established and others not so; in other words, those tobe established, necessarily, and others, each may be set at apredetermined value. Separation of the indications enables the user tosee the minimum items to be set. For example, when the user needs theinspection result soon, she/he may set only the necessary items to beset up, or when willing to make a tuning on the detection sensitivity,for example, she/he may set up the condition about the items, buy notnecessary to be set; therefore, degree of settings can be changeddepending on desire of the user. For example, in this embodiment, abutton 4306 displayed by triplicate frames around it indicates that itis an item, which must be established, necessarily, while a button 4307displayed by a single frame around it indicates that it is an item,being low in the necessity of setting thereof. Further, as othercharacteristics, a clear indication is made, for the user to know whichitem she/he is now setting up. For example, a button 4308 is displayedattaching the shade therewith, to be distinguished from the buttons 4306and 4307. In this manner, clear indication of the position at presentbrings about an advantage that the user can see the number of remainingitems to be set up at glance.

However, the present embodiment shows an example of adding an optioncondition setup 4309 to the sequence explained by referring to FIG. 30.The details of this option condition setup 4309 include, for example,setup of a size measuring function of foreign matters, and/or a setup ofclassifying condition of foreign matters and/or defects.

Next, detailed conditions 4302 are a screen for establishing the detailsof each of the conditioning items. As a method for inputting orselecting the items, it may be provided with a place to be inputtedthrough a keyboard, for example, in the form of an input box 4310, ormay be applied a method of selecting an input item with an aid of anicon, for example, in the form of an input icon 4311. However, the inputicon 4311 is an example of indicating the respective icons for three (3)kinds of input items, wherein another window comes out when pushing downone of those icons, so as to enable condition setup of the details.Furthermore, it may be a method of selecting a necessary item, such as,an input check box 4312, for example.

Also, the setout-contents display change button 4303 is that for makingchange or customizing the display items. For example, when there is anitem, on which the user always wishes to establish, or with which she/hewishes to increase the number of setting contents, this setout-contentsdisplay change button 4303 enables the user to make such changesthereupon; therefore, the user can obtain an easy screen to use, toestablish the inspection conditions, as quickly as possible. Further,the help button 4304 is for letting information to be outputted, for thepurpose of aiding the user when she/he looses the way of setting and/orcannot understand the contents of setting. As a method thereof, thecontents of the each setup item may be announced in the form of voiceguidance, or an operation method may be displayed through the movingpicture of MPEG, etc. Or, it is also possible for the user to talk witha designer of a maker, who produces the foreign-matter inspectingapparatus according to the present invention, on line, via a network ora telephone circuit.

[Embodiment Equipped with Microscope]

Explanation will be made about an embodiment, in relation to the defectsinspecting apparatus equipped with an observatory optical microscope,according to the present invention, by referring to FIGS. 1 and 33. Inthe present embodiment, an observatory optical microscope 60, comprisingan objection lens 61, a half-mirror 62, a light source 63 and a TVcamera 64, is provided in parallel with the illumination optic system 10and the detection optic system 200. This observatory optical microscope60 is provided for the purpose of moving the defects (including falseinformation) of foreign matters, etc., on the wafer 1, which aredetected through the signal processing system 40 of the defectsinspecting apparatus and memorized into the memory device 53, forexample, within a view field of the detection optic system 61-63 of theobservatory optical microscope 60, through movement of the stages 31 and32.

A merit of provision of the observatory optical microscope 60 inparallel with lies in that the defects, such as, the foreign matters,which are detected through the signal processing system 40 of thedefects inspecting apparatus, can be observed immediately, enlargedly,only through the movement of the stages 31 and 32, but without movingthe wafer onto the review apparatus, such as, the SEM, etc. In thismanner, the immediate and enlarged observation of the detected thingsthrough the defects inspecting apparatus enables quick identification ofreasons of generating the defects, such as, foreign matters, etc.

However, displaying an image thereof, which is picked up by the TVcamera 64 of the observatory optical microscope 60, enlargedly, as ascreen 66 shown in FIG. 34, on a color monitor 54 or 52, in common usewith a personal computer, for example, but there sometimes occur caseswhere the defects cannot be seen well, to be identified with the causeof generation thereof, i.e., the things detected through the defectsinspecting apparatus, depending on the kinds thereof, due to existenceof the circuit patterns. Then, since the total controller portion 50 candisplay the image, for example, in the form of 256×256 lines of pixels,on the display device 52, together with an image of the defects, whichare memorized into the data memory portion 1302 or the memory device 53,after being classified within the inspection-result integrationprocessor portion 1309 of the signal processing system 40 and detectedon the respective position coordinates thereof, it is possible toidentify the position on an enlarged image taken by the TV camera 64 ofthe observatory optical microscope 60, upon basis of the positioncoordinates and the image of that defects. As a result of this, withinthe observatory optical microscope 60, an area or a mark 67 indicativeof the identified defects mentioned above is displayed on the screen 66of the color monitor 54 or 52, and upon designation of that area or mark67 displayed, the defects are put within the view field of the detectionoptic system 61-63 through movement of the stages 31 and 32; therebyenabling the enlarged observation of the defects, immediately, even atthe position where the defects cannot be seen easily. In brief, sincethe position coordinates and the image of the defects, to be analyzed inthe details thereof, can be detected through the signal processingsystem 40 upon basis of the defects image signal, which is detected fromthe detection optic system 200, therefore, the detailed analysis can bealso made even on that defects, which cannot be seen easily, uponidentification of the area or mark 67 indicative of that defects on theenlarged image, which is picked up by the TV camera 64 upon basis of theposition coordinates and image of that defects detected, through theobservatory optical microscope 60, in the similar manner to the reviewapparatus, and as a result thereof, it is possible to estimate the causeof generation of that defects. Of course, since on the color monitor 54or 52 is displayed the area or mark 67 indicative of the defectsidentified, it is also possible to confirm on whether the detectionoptic system 200 and the signal processing system 40 actually detectsthe defects or not, on a side of the observatory optical microscope 60.

Further, the observatory optical microscope 60 may be a microscopehaving the light source 63 of visible lights (for example, a whitelight), or may be another microscope having the light source 63 ofultra-violet (UV) lights. In particular, for making an observation uponthe very fine or microscopic foreign matters of 0.1 μm, in the levelthereof, it is preferable to use the microscope having high resolution,such as, applying the ultra-violet (UV) lights therein. Or, using themicroscope of applying the visible lights therein brings about anadvantage that, color information can be obtained from, and the foreignmatters can be acknowledged easily.

INDUSTRIAL APPLICABILITY

According to the present invention, it is possible to make an inspectionof defects, such as, fine or microscopic foreign matters and/orscratches, etc., of a level of 0.1 μm, upon an inspection targetsubstrate, upon the surface of which is formed a transparent film, suchas, oxidation films, etc., and/or an inspection target substrate, on thesurface of which repetitive patterns are mixed up with non-repetitivepatterns, at high sensitivity and high seed.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential feature or characteristicsthereof. The present embodiment(s) is/are therefore to be considered inall respects as illustrative and not restrictive, the scope of theinvention being indicated by the appended claims rather than by theforgoing description and range of equivalency of the claims aretherefore to be embraces therein.

1. A defects inspecting apparatus, comprising: a stage for mounting aspecimen to be inspected and movable at least one direction; a firstilluminating unit which illuminates a surface of the specimen with afirst slit-like shaped polarized laser beam with a first incident angleto the surface of the specimen; a second illuminating unit whichilluminates the surface of the specimen with a second slit-like shapedpolarized laser beam with a second incident angle to the surface of thespecimen which is an angle greater than the first incident angle; afirst detecting optical unit installed in a first elevation angledirection to the surface of the specimen and having first image-formingoptics and a first image sensor to detect a first image of the specimenilluminated by the first illuminating unit or a second image of thespecimen illuminated by the second illuminating unit; a second detectingoptical unit installed in a second elevation angle direction to thesurface of the specimen which is an angle direction greater than thefirst elevation angle direction and having second image-forming opticsand a second image sensor to detect a third image of the specimenilluminated by the first illuminating unit or a fourth image of thespecimen illuminated by the second illuminating unit; and a processorwhich processes images detected by the first image sensor and the secondimage sensor to detect a defect on the specimen.
 2. A defect inspectingapparatus according to claim 1, wherein the first illuminating unitilluminates the surface of the specimen with a first ultraviolet laserbeam and the second illuminating unit illuminates the surface of thespecimen with a second ultraviolet laser beam.
 3. A defect inspectingapparatus according to claim 1, wherein the second image-forming opticsof the second detecting optical unit includes a polarizing plate.
 4. Adefect inspecting apparatus according to claim 1, wherein the firstimage-forming optics of the first detecting optical unit includes afirst spatial filter and the second image-forming optics of the seconddetecting optical unit include a second special filter.
 5. A defectinspecting apparatus according to claim 1, wherein the firstilluminating unit illuminates the specimen with the first slit-likeshaped polarized laser beam in a longitudinal direction of the slit-likeshaped polarized laser beam.
 6. A defect inspecting apparatus accordingto claim 1, wherein the second detecting optical unit is installed in aperpendicular direction relative to the surface of the specimen.
 7. Adefect inspecting apparatus according to claim 1, wherein a magnitude ofan image formed by the second image-forming optics of the seconddetecting optical unit is variable.
 8. A defect inspecting apparatusaccording to claim 1, wherein the first image sensor of the firstdetecting optical unit and the second image sensor of the seconddetecting optical unit are linear image sensors.
 9. A defect inspectingapparatus comprising: a stage for mounting a specimen to be inspectedand movable at least in one direction; an illuminating optical unithaving a first illuminator which illuminates a surface of the specimenwith a first slit-like shaped polarized laser beam with a first incidentangle to the surface of the specimen, and a second illuminator whichilluminates the surface of the specimen with a second slit-like shapedpolarized laser beam with a second incident angle to the surface of thespecimen which is an angle greater than the first incident angle; adetecting optical unit having first detection optics installed in adirection of a first elevation angle to the surface of the specimen todetect light from the specimen caused by the illuminations theilluminating optical unit and a second detection optics installed in adirection of a second elevation angle to the surface of the specimen todetect light from the specimen caused by the illumination by theilluminating optical unit; and a processor which processes imagesdetected by the first detection optics and the second detection opticsto detect defects on the specimen and classifies the detected defectsinto one of plural defect categories; wherein the first illuminator ofsaid illuminating optical unit illuminates the specimen with the firstslit-like shaped polarized ultraviolet laser beam in a longitudinaldirection of the first slit-like shaped polarized ultraviolet laserbeam, and first illuminator and said second illuminator illuminate thespecimen at different times.
 10. A defect inspecting apparatus accordingto claim 9, wherein the illuminating optical unit includes a laser lightsource to emit an ultraviolet laser beam, and a switching means forswitching a path of the emitted ultraviolet laser beam between the firstilluminator and the second illuminator.
 11. A defect inspecting method,comprising the steps of: illuminating a surface of a specimen with afirst slit-like shaped polarized laser beam with a first incident anglerelative to the surface of the specimen; detecting a first image of thespecimen illuminated by the first slit-like shaped polarized laser beamwith a first detecting optical unit installed in a first elevation angledirection to the surface of the specimen and detecting a second image ofthe specimen illuminated by the first slit-like shaped polarized laserbream with second detecting optical unit installed in a second elevationangle direction to the surface of the specimen which is an elevationangle greater than the first elevation angle; illuminating the surfaceof the specimen with a second slit-like shaped polarized laser beam witha second incident angle relative to the surface of the specimen which isan angle greater than the first incident angle; detecting a third imageof the specimen illuminated by the second slit-like shaped polarizedlaser beam with the first detecting optical unit installed in the firstelevation angle direction and a fourth image of the specimen illuminatedby the second slit-like shaped polarized laser beam with the seconddetecting optical unit installed in the second elevation angledirection; and processing the detected first image, second image, thirdimage and fourth image to detect defects on the specimen and classifyingdefects detected by the detection.
 12. A defect inspecting methodaccording to claim 11, wherein the first detecting optical unit and thesecond detecting optical unit each include a spatial filter, and thefirst image, the second image, the third image and the fourth image aredetected after passing through the spatial filter.
 13. A defectinspecting method according to claim 11, wherein the first slit-likeshaped polarized laser beam is incident to the surface of the specimenfrom a longitudinal direction of the slit-like shaped polarized laserbeam.
 14. A defect inspecting method according to claim 11, wherein thesecond detecting optical unit detects the second image and third imagefrom a perpendicular direction to the surface of the specimen.
 15. Adefect inspecting method according to claim 11, wherein a magnitude ofan image formed by image-forming optics of the second detecting opticalunit is variable.
 16. A defect inspecting method according to claim 11,wherein the first detecting optical unit and the second image sensor ofsaid second detecting optical unit include linear image sensors.